Overlapping boundary electron exposure system method and apparatus

ABSTRACT

An electron beam exposure apparatus and method for use in fabricating semiconductor devices. A chip pattern larger in area than the electron beam scan field is divided into and exposed in a number of smaller parts (called partitions). The work piece on which the chip pattern is to be formed is moved relative to the scan field to enable each partition to be individually scanned at a different work piece position. The scan field, with the work piece positioned to scan one partition, overlaps onto and establishes a boundary region on an adjacent partition. Portions of chip patterns which lie in a boundary region are selectively scanned in connection with one or another of the abutting partitions. Portions of chip patterns falling in the boundary regions are selected for scanning in one or the other of adjacent partitions so as to minimize the number of divisions and so as to avoid dividing the pattern along critical dimensions.

CROSS REFERENCE TO RELATED APPLICATIONS

ELECTRON BEAM SYSTEM, Ser. No. 847,485, filed Nov. 11, 1977, invented by Fred K. Buelow and John J. Zasio and assigned to the assignee of the present invention.

BACKGROUND OF THE INVENTION

This invention relates to the fabrication of microminiature devices and, more particularly, to an automated, high-speed electron beam apparatus and method for making such devices.

It has long been known that the high-resolution and excellent depth-of-focus capabilities of an electron beam make it a practical tool for inclusion in an automated system for making microminiature electronic devices. The electron beam is controlled in a highly accurate and high-speed manner to expose an electron-resist-coated material as a step in the fabrication of extremely small and precise low-cost integrated circuits.

Although an electron beam can be deflected and blanked in a high-speed manner, the scan area over which the beam is capable of being accurately deflected is relatively small. A basic problem presented, therefore, is how to utilize an electron beam which has a small-area scan field to rapidly and accurately expose relatively large chip pattern areas.

In addition to the need for exposing large areas, large densities of circuits are desired on semiconductor chips. The trend in the industry has been towards a greater number of circuits per unit of area and towards smaller circuit elements. With this trend, it has become increasingly possible to integrate an entire system or subsystem on one or a relatively few number of semiconductor chips.

In order to accommodate the greater density of circuits and to obtain the accuracy required for smaller circuit elements, electron beam systems are employed to scan chip patterns or portions of chip patterns each covering an area which is equal to or less than the scan field area which can be accurately scanned by the electron beam.

When the chip pattern to be scanned covers an area greater than the area which can be accurately scanned by the electron beam, the chip pattern is divided into partitions where each partition has an area which is small enough to fit within the scan field of the electron beam. The partitions are then scanned one at a time. After scanning each partition, the work piece (wafer or other material to be scanned) is moved so that the electron beam scan field is relocated for scanning the next adjacent partition. In this manner, the entire chip pattern is scanned one partition at a time.

In order that the composite chip pattern be accurately scanned, each partition must be accurately scanned. Furthermore, adjacent partitions must be properly aligned (that is, properly registered) with respect to each other. Failure to have proper registration means that circuit elements crossing the boundry between partitions will be misaligned. This problem of partition alignment is a problem of registering the electron beam scan field on the work piece each time the work piece is moved.

Problems arise in connection with the registration of the scan field particularly when circuit elements having critical dimensions are located at or near the boundary between adjacent partitions. If a circuit element having a critical dimension is located across a partition boundary, portions of the circuit element will normally be scanned at two different times with two different positions of the work piece relative to the electron beam scan field.

If the electron beam scan field position at one location of the work piece is misaligned relative to its position at an adjacent position of the work piece, then an error due to the misalignment will be introduced into the scanning of the circuit element crossing the boundary. If the magnitude of the misalignment is large with respect to critical dimensions of the circuit element being scanned, the circuit element will be significantly malformed.

The problem of how to accurately register and reregister the scan field on a work piece is well known. Many different solutions for this problem have been proposed and have been employed with various degrees of success. Many of these solutions employ alignment marks within each partition for use in connection with registering the scan field when the work piece is moved. While the use of alignment marks in various forms is useful and desirable, there is still a need for an improved method and apparatus for avoiding the problems caused by misalignment of adjacent partitions.

In accordance with the above background of the invention, it is an object of the present invention to provide an improved electron beam apparatus and method for successively scanning smaller partitions to form a larger composite chip pattern.

SUMMARY OF THE INVENTION

The present invention is an electron beam apparatus and method for scanning a chip pattern. The chip pattern is divided into partitions, each smaller than the overall chip pattern. Also, each partition is smaller than the scan field of the electron beams. The partitions are scanned by the electron beam one at a time so that the overall chip pattern is formed as a composite of the individual partitions. A work piece on which the chip pattern is to be scanned is moved to a different position relative to the electron beam scan field each time a different partition is to be scanned.

Since the scan field of the electron beam is larger than each partition, the scan field positioned to scan one partition overlaps onto an adjacent partition. Each partition, therefore, has a boundary region which is overlapped by the scan field at more than one position of the work piece. Any portion of the chip pattern which falls within such a boundary region may be scanned at more than one position of the work piece. Since only one scanning is desired, a selection is made, in accordance with the present invention, as to which position of the work piece such a portion of the chip pattern is scanned. The selection is made so as to minimize the division of circuit elements and so as to avoid division of circuit elements in those regions which have critical dimensions and which would, therefore, cause registration problems.

Accordingly, those portions of a circuit element having critical dimensions tend to be exposed in a single scanning with the work piece at one location. In this manner, such critical dimensions are accurately scanned and are immune to any misalignment of the electron beam scan field when the work piece is moved from one position to an adjacent position.

In accordance with the above summary, the present invention achieves the objective of providing an improved electron beam apparatus and method for scanning an electron beam to expose a chip pattern by means of overlapping boundary scan fields and selective scanning of portions of the chip pattern.

Additional objects and features of the invention will appear from the following description in which the preferred embodiments of the invention have been set forth in detail in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts an overall electrical schematic block diagram of an electron beam apparatus in accordance with the present invention.

FIG. 2 depicts one of the two table controls which form part of the FIG. 1 apparatus.

FIG. 3 depicts a line generator which is one component within the FIG. 1 apparatus.

FIG. 4 depicts a representation of the electron beam scan field produced by the FIG. 1 apparatus.

FIG. 5 depicts a top view of the table and work piece which are utilized in the FIG. 1 apparatus.

FIG. 6 depicts a representation of the FIG. 4 scan field at a reduced scale.

FIG. 7 depicts a chip area formed by a plurality of adjacent scan fields of the FIG. 4 type at the scale shown in FIG. 6.

FIG. 8 depicts a typical chip area having a chip pattern which has been partitioned in accordance with the present invention.

FIG. 9 depicts an expanded view shown along a line between two of the partitions of FIG. 8.

FIG. 10 depicts a view of a processed first one of the two partitions of FIG. 9.

FIG. 11 depicts a view of a processed second one of the two partitions of FIG. 9.

FIG. 12 depicts a representation of how the chip pattern partitioning is performed.

DETAILED DESCRIPTION Overview-FIG. 1

In FIG. 1, a wafer or other work piece 2 to be exposed by an electron beam is positioned on the motor-driven table 24. The table 24 is located within the work chamber 80 of an electron beam column 76. The column 76 is a conventional device including an electron source 77, a blanking unit 78, a deflection unit 79, a work chamber 80, and an interferometer unit 81. The column 76 is typically like that manufactured by ETEC Corporation of Hayward, California.

The electron source 77 provides the electrons which are incident upon the work piece 2 on the table 24. Blanking unit 78 permits the electron beam to be focused on the work piece or blanks the electron beam to inhibit electrons in a conventional manner. The blanking unit 78 is selectively controlled to inhibit or pass the electron beam by the beam blanking control line 52 from the line generator 28.

The deflection unit 79 includes both X and Y deflection coils (not shown) for positioning the electron beam in the X and Y axes. The X coil is driven by the output from the X sum circuit 36. Similarly the Y coil is driven by the Y sum circuit 36'.

The sum circuits 36 and 36' provide the X and Y drive signals to the deflection unit by summing a number of input signals. First, the sum circuits 36 and 36' receive the IX and IY commanded position signals as inputs from converters 32 and 32', respectively, which in turn are commanded by the line generator 28 and processor 26. The IX and IY signals specify the location of the electron beam with respect to a unit size in some predetermined coordinate system. In one embodiment, the unit size is 0.5 × 10⁻⁶ meter.

The sum circuits 36 and 36' also receive correction signals IDX and IDY, respectively, which correct the position of the electron beam with some correction unit size as a function of the measured position of the movable work piece 2 as measured by an interferometer unit 81. In one embodiment, the size of the correction signal is in units of 0.08 × 10⁻⁶ meter. Accordingly, one unit of the IX position command signal (0.5 × 10⁻⁶ meter) summed with one unit of the IDX correction signal (0.08 × 10⁻⁶ meter) specifies a deflected distance of 0.58 × 10⁻⁶ meter. Similarly, ten units of IX (5.0 × 10⁻⁶ meter) and 20 units of IDX (1.6 × 10⁻⁶ meter) specifies a deflected distance of 6.6 × 10⁻⁶ meter.

The sum circuits 36 and 36' also receive rotation signals IRX and IRY, respectively, from units 131 and 131' for rotating the XY electron beam axes relative to the X'Y' axes of table 24. In FIG. 1, the work table 24 is driven in the X-axis direction by the X axis motor 20 and in the Y-axis direction by the Y axis motor 20' to precisely position the work piece 2 relative to the incident electron beam. The actual position of the work piece 2 and the table 24 is measured by the interferometer unit 81. Typically the interferometer unit 81 includes an interferometer for measuring the X axis position which provides an X position output 22. Similarly, the interferometer unit 81 includes a Y axis unit providing a Y position output 22'. One typical interferometer unit is manufactured by Hewlett Packard Corporation and is model number HP5501. Such a unit provides a 24-bit output which is capable of measuring the actual position of the work piece 2 and table 24 to approximately 0.08 × 10⁻⁶ meter. The interferometer unit is capable of tracking movements at rates of approximately up to 15 centimeters per second. The X and Y position outputs 22 and 22' from the interferometer unit 81 are connected as inputs to the X and Y axis table controls 10 and 10' respectively. Controls 10 and 10' provide signals to the units 34 and 34' to generate the correction signals IDX and IDY, respectively. In FIG. 1, the control circuitry for controlling the electron beam column 76 includes a computer 4 which commands the operation of the system in the exposure of the work piece 2 by the electron beam. Computer 4 in one typical embodiment is a Hewlett Packard model HP21MX. Computer 4 connects over a conventional digital interface 5 to the data bus 6. The computer 4 is also connected in a conventional way to I/O devices such as a CRT console 69, a magnetic tape unit 70 and a magnetic disc unit 71. The computer 4 controls the remainder of the system.

The computer 4, through the digital interface 5, communicates with a number of addressable units connected to bus 6. Bus 6 is typically a 16-bit bus with appropriate conventional selection means (not shown) for selecting an addressed one of the units connected to bus 6.

In FIG. 1, the units connected to bus 6 include the memory 7, the X gain control 8, the Y gain control 8', the X rotation control 11, the Y rotation control 11', the X table control 10 and the Y table control 10'.

Memory 7 is a random access memory typically storing 2,048 or more 16-bit words. The X and Y gain controls 8 and 8' are typically digital-to-analog converters (DAC). When selected by the digital interface 5, the controls 8 and 8' convert the digital outputs to analog levels on lines 9 and 9', respectively. Lines 9 and 9' each connect as a reference (R) input to the X and Y deflection DAC's 32 and 32'. The DAC's 8 and 8' and the DAC's 11 and 11' are conventional devices of the type which typically receive a 10-bit input to responsively provide one of 1024 levels for the analog signal output. Such devices are conventional and in one typical embodiment are manufactured by Burr Brown with model number 60-10. Since those DAC devices do not have means for storing the digital signals from bus 6, each of the DAC's 8, 8', 11 and 11' are shown in FIG. 1 to include conventional registers 8-1, 8'-1, 11-1, and 11'-1 for storing the digital data, respectively, under command of the interface 5.

When exposing the work piece 2 to form a pattern thereon, it is important that the deflection gain of the electron beam be accurately controlled so that the actual size of the electron beam scan field on the work piece 2 corresponds to the desired size of the electron beam scan field. The gain controls 8 and 8' are utilized for controlling the size of the electron beam scan field. When the beam deflection exceeds or is less than required for the desired scan field size, the deflection gain signals from controls 8 and 8' are controlled to appropriately adjust the respective referenced inputs to the converters 32 and 32'.

The X and Y rotation controls 11 and 11' are digital-to-analog converters (DAC) of the same type as the converters for controls 8 and 8'. The controls 11 and 11' convert digital outputs from the computer 4 into an analog level on lines 13 and 13', respectively. Lines 13 and 13' are each connected to one of the inputs of the multiplying amplifiers 131 and 131', respectively. The other input to amplifier 131 is supplied from the output of the Y converter 32'. Similarly, the other input to the amplifier 131' is supplied from the output of the X converter 32. The amplifiers 131 and 131', respectively, provide output signals which are connected in common with and summed with the outputs of the X and Y deflection converters 32 and 32', respectively, in the sum circuits, 36 and 36', respectively.

In FIG. 1, it is desired that the scanning axes, X and Y, of the electron beam coincide with the axes X' and Y' of the table 24, and with the axes, X" and Y", of the work piece 2. The three sets of axes XY, X'Y' and X"Y" are shown with a common origin in FIG. 1. In order to bring the axes into common alignment, rotation of the electron beam axes XY is useful. The rotation controls 11 and 11' are utilized for adjustably rotating the axes XY of the electron beam relative to the axes X'Y' of the table and the axes X"Y" the work piece 2. In operation, digital signals specifying the degree of rotation are supplied from the computer 4 to the inputs of the rotation controls 11 and 11'. The outputs from control 11 and 11' in turn control the rotation by controlling the electron beam deflection through operation of the sum circuits 36 and 36' and the amplifiers 131 and 131'.

The rotation controls 11 and 11' are also utilized for controlling the perpendicularity of the electron beam scanning in response to the digital outputs from the computer 4. Perpendicularity of the electron beam scanning refers to the X axis movement relative to the Y axis movement.

In FIG. 1, the X and Y table controls 10 and 10' receive data from and connect data to the 16-bit bus 6. Controls 10 and 10' are shown in further detail in FIG. 2. Briefly, the control 10 receives a commanded position from the bus 6. The commanded positon from bus 6 is converted to the drive signal on line 16 for driving the X motor drive 18. The X motor drive 18 in turn drives the X motor 20 to position the X axis of the table 24 within the chamber 80. Similarly, the Y table control 10' via line 16' energizes the Y motor drive 18' which in turn energizes the Y motor 20'. The Y motor 20' drives the table 24 to the desired Y axis position. The motor drive 18 and 18' and the motors 20 and 20' are conventional devices for indexing a motor-driven table. A typical motor drive and motor employed in one preferred embodiment of the invention is manufactured by Torque Systems Inc. having model number RL 3260E. Such a system has a capacity of driving the table 24 at a rate of approximately 5 centimeters per second, and accelerating or decelerating at a rate of 10 meters/sec² (approximately 1G).

In addition to commanding the actual position of the table 24, the table control 10 and 10' also compare the commanded position (received over bus 6) with the actual position measured by the interferometer unit 81. The difference between the commanded position and the actual position is utilized to generate a correction signal on the 10-bit buses 14 and 14' for the controls 10 and 10', respectively. The 10-bit correction buses 14 and 14' are connected as inputs to the X and Y position correction DAC's 34 and 34'. The table 24 can be positioned by the motor drives 18 and 18' within an accuracy of about 0.24 micron from the commanded position. In order to provide higher accuracy as is necessary for scanning small areas, the converters 34 and 34' are utilized. The converters 34 and 34' form the analog correction signals IDX and IDY. The correction signals IDX and IDY are summed with the line scan signals IX and IY, respectively, in the sum circuits 36 and 36'. The line scan signals IX and IY are generated by the X and the Y deflection digital-to-analog converters (DAC) 32 and 32', respectively.

The converters 32 and 32' are of the same type as the converter 8 and 8'. Converters 32 and 32' are driven by inputs from the line generator 28 which is in turn driven by the line processor 26.

The line processor 26 is typically a conventional microprocessor such as the Motorola 6800. The line processor 26 accesses data for a line scan from the memory 7. Processor 26 then loads the line generator 28 with data sufficient for one line scan. The line generator 28 then is clocked at a high data rate loading the appropriate values into the converters 32 and 32' to perform a line scan at a high data rate. Converters 32 and 32' generate the line drive signals IX and IY in response to the outputs from line generator 28 as adjusted by the reference levels output from the gain controls 8 and 8'. Any correction factors required for drive signals IX and IY are derived from the converters 34 and 34' and the controls 11 and 11' which are all summed in the sum circuits 36 and 36'. The sum circuits 36 and 36' in turn drive the deflection unit 79 to actually position the electron beam.

The line generator 28 receives data from the line processor 26 via the 16-bit bus 57. Generator 28 in turn generates 10-bit deflection commands on output buses 53 and 53' which are connected to the X converter 32 and to the Y converter 32', respectively. Generator 28 also provides an output signal on line 52 which controls the blanking unit 78.

Line generator 28 provides a zero detect output line 51 which connects to the line processor 26. Zero detect line 51 signals the line processor 26 to indicate when the line generator 28 has completed a line scan. When generator 28 has completed a line scan, processor 26 immediately loads the generator 28 with a new line command and scanning continues in this manner.

The line generator 28 functions to inhibit line scanning whenever a STOP SCAN signal is drived on the lines 12 or 12' from the X and Y table controls 10 and 10'. The STOP SCAN signals signify that the commanded position of the table 24 relative to the actual position of table 24 exceeds a predetermined error (for example, greater than correctable by the 10-bit correction signal). Whenever this predetermined error is exceeded, the STOP SCAN signal functions to inhibit further operation of the line generator until the error is reduced to within the acceptable limits.

Table Control-FIG. 2

In FIG. 2, further details of the table controls 10 and 10' of FIG. 1 are shown. In FIG. 2, only the X table control 10 is actually shown since the Y table control 10' is identical.

In FIG. 2, the 16-bit bus 6 from the digital interface 5 is selectively gated to the commanded position register 42 and the maximum error register 48. The commanded position register 42 is a 24-bit register which receives the full 16-bits of bus 6 as one field and 8 bits of bus 6 as a second field. The lowest-order bit (and each count) in register 42 represents a distance of 0.08 × 10⁻⁶ meter. The fields are separately addressed by the computer 4 of FIG. 1 and are separately selected at different times by the digital interface 5 in a conventional manner for computers. At still a different time, a 10-bit field of the 16-bit bus 6 is selected for the maximum error register 48. The lowest-order bit (and each count) in register 48 represents a distance of 0.08 × 10⁻⁶ meter.

In FIG. 2, the actual position register 43 is a 24-bit register for receiving the actual position data from the 24-bit bus 38 from the interferometer unit 81 of FIG. 1. The lowest-order bit (and each count) in register 43 represents a distance of 0.08 × 10⁻⁶ meter. The 24-bit outputs from the commanded position register 42 and the actual position register 43 are subtracted in a conventional 24-bit subtractor 44. The output from this subtractor is connected on a 24-bit bus to a 24-bit error register 45. The contents of the error register 45 are gated selectively to a number of locations in a number of field sizes. A low-order 16-bit and a high-order 8-bit field connect to the bus 6 for returning data through the digital interface 5 to the computer 4 of FIG. 1. The high-order 12 bits from error register 45 are input to the gate control 41. The low-order 12 bits from the register 45 are input to the error limit register 46. The low-order 10 bits connect to the magnitude comparator 49 and connects an output on bus 14 to a position correction DAC 34 in FIG. 1. The high-order 14 bits from register 45 connect to the control 41'.

Control 41, in one embodiment, is an EXCLUSIVE-OR gate network (not shown) for examining the 12 high-order bits from register 45. For positive errors less than +4095 (2¹² -1), such network detects the all 0's condition of the 12 high-order bits. For positive errors greater than +4095, the network detects a 1 in any of the 12 high-order bit positions. In a similar manner, the network also detects for negative errors greater than or less than -4096 (-2¹²).

If control 41 detects an error greater than +4095 (2¹² -1) in register 45, it forces the error limit register 46 to the binary equivalent of +4095 producing the maximum negative velocity of the servo.

If control 41 detects an error less than -4096 (-2¹²) in register 45, it forces the error limit register 46 to the binary equivalent -4096 producing the maximum positive velocity of the servo.

If the error is between the above two limits (+4095 and -4096), the error value in register 45 is fed directly to register 46 and then to converter 47 producing a servo motor velocity signal on line 16 proportional to the error value. This proportional velocity signal provides an overdamped drive response to the servo motor system while allowing it to accurately position the table 24 to an accuracy of less than one micron.

The contents of error register 45 and maximum error register 48 are fed to magnitude comparator 49. If the magnitude of the error exceeds the value in register 48, a STOP SCAN signal is provided to the line scan generator 28 of FIG. 1.

The 10 low order bits of register 45 also form the 10-bit bus 14 which forms the position correction signal for the position correction converter 44 of FIG. 1.

By way of summary, the table control of FIG. 2 includes a means for driving the table with a signal having a magnitude proportional to the difference between the commanded position and the actual position of the table, includes means for providing a position correction signal proportional to the difference between the commanded position and actual position of the table and provides a STOP SCAN signal whenever the difference between the commanded position and the actual position exceed a predetermined error.

Line Generator-FIG. 3

In FIG. 3, the line generator 28 of FIG. 1 is shown in greater detail. The line generator functions to provide signals to the deflection unit 79 for commanding the electron beam to scan a line at a time in discrete steps. The X location of the beam is stored in the X beam position up/down counter 60. The Y location of the beam is stored in the Y beam position up/down counter 60'. The number of steps to be scanned (in either the X or Y directions) is stored in counter 58. The lowest-order bit (and each count) in each of the counters 58, 60 and 60' represents a distance of 0.5 × 10⁻⁶ meter. Scanning occurs for the number of steps represented by the count in length counter 58. Counter 58 and either the X counter 60 or Y counter 60' are incremented to cause the electron beam to be scanned. The 16-bit bus 57, from the processor 26 of FIG. 1, connects to the 10-bit length counter 58, to a 2-bit register (not shown) in the control unit 59, and to the 10-bit beam position counters 60 and 60'.

The line processor 26 supplies three 16-bit words to the line generator 28 when it receives a zero detection signal on line 51. Control unit 59 in FIG. 3 controls the distribution of the three words in the following manner. Upon receipt of the zero detection signal from detector 50, the control unit 59 is reset to parallel load the three low-order 10 bits of the first, second and third words from bus 57 into the X beam position counter 60, the Y beam position counter 60', and into the length counter 58, respectively, during first, second, and third stages of a load sequence. During the first stage, control unit 59 provides a control signal on line 61 to the X beam position counter 60 to cause counter 60 to parallel store the low-order 10 bits of data from bus 57 (which specifies a coordinate in the X axis of the beam).

After the counter 60 has received the first word, the control unit 59 sequences to the second stage and provides the control signal on line 62 to cause the Y beam position counter 60' to parallel store low-order 10 bits from bus 57 specifying a coordinate in the Y axis of the beam.

After receipt of the second word, the control unit 59 is stepped to the third stage. The control unit 59 provides the control signal on line 63 to cause the counter 58 to parallel store the low-order 10 bits of the third word from bus 57. Control unit 59 also on the third stage stores the two high-order bits of the third word. The two high-order bits, BIT 14 and 15, designate the direction of scan (positive or negative) and the axis of scan (X or Y).

Upon the receipt of the two high-order bits, the control unit 59 is stepped to the operating stage removing the beam blanking signal on line 52 and enabling the clock signal to counter 58. The control unit 59 then steps the counter 58 at the clock rate (for example, 10⁷ Hz or greater) until the length counter 58 is counted down to zero.

Meanwhile, the control unit 59 provides the control signals on lines 64 and 65. The control signal on line 64 causes one of the counters 60 and 60' to step up or down in accordance with the BIT 14. The other control signal, on line 65, causes the counter 58 to provide a signal generated at each step thereof to the X or Y beam counter 60 or 60', whichever one corresponds to the scan axis, as determined by the BIT 15. If BIT 15 is a logical 1, then the counter 60 is counted by the signal on line 66 from the counter 58 while counter 60' is not counted. If BIT 15 is a logical 0, the the counter 60' is counted by the signal on line 66' while counter 60 is not counted. The 10-bit outputs on lines 53 and 53' from counters 60 and 60' connect to converters 32 and 32'.

When the length counter 58 is counted down to zero, the zero detector 50 senses a zero, resets the control unit 59 to the beginning of the sequencing stage and signals the processor 26 to send a sequence of three additional words.

If at any time during the scanning mode either of the STOP SCAN lines 12 or 12' signals to stop the scanning, the control unit 59 inhibits clock outputs and generates the BEAM BLANK signal until neither STOP SCAN signal is present.

Field Scan - FIG. 4

In FIG. 4, the scan field 102 produced by the electron beam column 76 of FIG. 1 is shown in greater detail. The scan field 102 covers an area 512 by 512 microns (512 × 10⁻⁶ meters square). That area is divided into 1,048,576 addressable locations where each location appears at the intersection of one of 1,024 rows and one of 1,024 columns. The columns are defined by the 10-bit X address and the rows are defined by the 10-bit Y address previously described in connection with the line generator of FIG. 3. The line generator of FIG. 3 causes the electron beam to be deflected so as to be incident at any one of the 1,048,576 locations specified by a row address and a column address.

In a typical embodiment, the electron beam spot size is 0.5 micron in diameter. With this spot size for the electron beam and with the 1,024 addresses per axis, the entire 512 by 512 micron scan field or any part thereof, may be exposed by the electron beam.

In connection with FIG. 4, an example of how the present invention operates to scan a particular part of a circuit is described. In FIG. 4, the scan field 102 includes in the lower left hand corner a printed circuit conductor 103 which terminates in a printed circuit land 104. The conductor 103 is 3 microns wide, has a right angle and terminates in a land 104 which is 5 microns square. Assumming, for purposes of explanation, that the scanning of the conductor 103 and land 104 is to occur in the X direction, then the following addresses are generated by the line generator of FIG. 3.

In the manner previously indicated in conjunction with FIG. 3, the X beam position counter 60 is loaded with a 10-bit binary word which specifies column 5.

Thereafter, the Y beam position counter 60' is loaded with another 10-bit binary word which specifies row 3. The outputs of the counters 60 and 60' are fed to the X deflection DAC 32 and the Y deflection DAC 32', to cause the electron beam to be positioned at the point of column 5 and row 3.

Meanwhile, the length counter 58 is loaded with still another 10-bit word representing the distance to the last location of the conductor 103 in row 3, which is column 20. At the same time, the control unit 59 receives BIT 14 as a logical 1 and BIT 15 as a logical 1, which together, indicate that the scanning is to occur in the positive X direction. After the loading has been completed, the beam blanking signal on line 52 is removed and the X axis address in the X beam position counter 60 is incremented until the length counter 58 reaches a zero count. Incrementing occurs because BIT 14 and BIT 15 are logical 1's. When the count in length counter 58 reaches zero, the beam blank signal is turned on and no further exposure in row 3 will occur. The zero detector 50 causes the control unit 59 to load three new 10-bit numbers for the next scanning line. An identical 10-bit number indicating column 20 is stored in the X beam position counter 60, and the Y beam position counter 60' is loaded with a 10-bit number which indicates row 4. Then, the X and Y DAC's 32 and 32' supply analog signals to position the beam at the column 20 and row 4 location.

A length count of 15 is loaded into counter 58 and the control unit 59 detects BIT 14 as a logical 0 and BIT 15 as a logical 1.

Therefore, the X beam position counter is decremented and the beam is moved in the negative X direction while scanning the row until the length counter reaches a zero count. Scanning in this manner for each row for columns 5 through 20 continues.

After the scanning has been performed for row 8, new numbers specifying column 15 and row 9 are stored respectively into the X beam position counter 60 and the Y beam position counter 60', and then the length counter 58 is loaded with a length count of 6. Scanning with this length count of 6 is carried out for each of the rows 9 through 14, while the initial count in the counter 60 is changed to 15 for rows 9, 11 and 13 and to 20 for rows 10, 12 and 14 and the count in the Y counter 60' is incremented by one for each row from 9 to 14.

Thereafter, the scanning for the land 104 is started by entering the Y address for row 15 into the Y beam position counter 60' and the X address for column 13 into the X beam position counter 60. The length count is 10 and is loaded into the length counter 58. Each of the rows 15 through 24 is scanned with a length of 10 in order to complete scanning of the land 104.

All of the scanning of the conductor 103 and land 104 in FIG. 4 occurs without any requirement that the table 24 of FIG. 1 be moved.

It should be observed that the data rate for scanning the pattern comprising the conductor 103 and the land 104 is determined by the bit rate of data from the counters 58, 60 and 60'. That bit rate is defined by the clock rate at which the counters 58, 60 and 60' are stepped. In the present invention, time is not wasted scanning areas of the scan field 102 which are not to be exposed by the electron beam. While the data bit rate of scanning is the rate of clocking counters 58 and 60, the data rate for loading three words into the line generator 28 is also important in maintaining a high data rate because three words must be accessed for each line to be scanned by the line generator 28. On the other hand, the data rate between the line processor 26 and the computer 4 need only be at a rate great enough to exceed the line rate of scanning. For example, a data rate of 10⁶ words per second between computer 4 and processor 6 (on a non-continuous burst mode basis) normally sustains a 10⁸ bit per second data rate between line generator 28 and column 76.

Table Position -- FIG. 5

In FIG. 5, the table 24 and work piece 2 of FIG. 1 are shown in greater detail. The work piece 2 is typically a semiconductor wafer of approximately 100 millemeters in diameter. The wafer 2 has a center indicated by the intersection of the X' and Y' axes. The electron beam from electron beam column 76 of FIG. 1 is incident upon the wafer 2 at a location indicated by the intersection of the X and Y axes. The table 24 and wafer 2 are relatively movable with respect to the incident electron beam. Therefore, the X' Y' axes are relatively movable with respect to the XY axes through movement of the table 24. In FIG. 5, the point of incidence (intersection of X and Y) of the electron beam is shown in the lower left quadrant of the X' Y' axes. In FIG. 5, the area of incidence of the electron beam is at one row and one column address within a scan field of the FIG. 4 type. That scan field is in turn within one of many chip areas. The particular chip area 101-1 over which the scan field of the electron beam is incident is determined by the position of the table 24 as defined by axes X' Y'. The chip areas 101 are areas which can be ultimately diced and then packaged to form individual integrated circuits. A chip area can be and typically is larger than the scan field of the electron beam. Therefore, each chip area is divided into partitions which can be individually exposed by the beam scan field. The table 24 and wafer 2 are moved to superimpose the beam scan field over a selected chip area and over a selected partition within a chip area.

In FIG. 5, the electron beam axes X' Y' is located to position the electron beam scan field over a chip area 101-1. The scale of FIG. 5 does not allow the partitions of the chip area 101-1 to be observed.

In one application of the present invention, the beam scan field 102 as shown in FIGS. 4 and 6, is typically 512 by 512 microns and the chip area 105, as shown in FIG. 7, is typically 1350 by 1606 microns. Since the scan field 102 is smaller than the chip area 105, the chip area 105 is divided into twelve partitions 106. Each partition 106 is smaller than the scan field 102. Each partition is positioned, at a different time, to be superimposed by the electron beam scan field so that twelve different positions of the table 24 and wafer 2 are needed to permit one chip area 105 to be fully scanned by the electron beam.

In FIG. 5, the electron beam scan field is positioned over the chip area 101-1. Wafer 2 will accomodate hundreds of other chip areas of the same size, some of which are represented by chip areas 101 in FIG. 5. The table 24 is positionable to locate any chip area 101 (and any partition of a chip area) beneath the electron beam scan field.

Chip Area Formation By Overlapping Scan Fields -- FIGS. 6 & 7

In FIG. 6, a scale representation of the electron scan field 102 like that previously described in FIG. 4 is shown.

In FIG. 7, a chip area 105 is shown having the dimensions of 1,606 microns by 1,350 microns. The chip area 105 is further divided into the partitions 106 and specifically the twelve partitions 106-1, 106-2, . . . , 106-12. The partitions are each smaller than the scan field 102 of FIG. 6. For example, the partitions are 450 microns by 401.5 microns in a typical example. Note that each of the partitions 106 of FIG. 7 can be totally enclosed within the scan field 102 shown to the same scale in FIG. 6.

In FIG. 7, the scan field 102 of FIG. 6 is shown positioned relative to the partition 106-7. When so positioned, the scan field 102 is designated as scan field 102-7. The scan field 102-7 is designated by long broken lines in FIG. 7. Also in FIG. 7, the scan field 102 is shown positioned over the partition 106-8 and the scan field is shown as short broken lines and is designated as scan field 102-8. The boundary line 120 (7/8) between partitions 106-7 and 106-8 is covered both by the scan field 102-7 and the scan field 102-8. There is a region 122 having a dimension B2 which is common to both the scan field 102-7 and the scan field 102-8. In accordance with the present invention, electron beam scanning within the region 122 can be performed either in connection with the scan field 102-7 or in connection with the scan field 102-8. While only the partitions 102-7 and 102-8 have been indicated showing the overlapping scan field relationship, each of the partitions in FIG. 7 and the adjacent partitions on any side similarly have an overlapping boundary relationship relative to the electron beam scan fields.

The purpose of this overlapping boundary relationship is to permit portions of the chip pattern which lie within the overlapping boundary region, such as region 122, to be selectively processed either in one scan field (eg. 102-7) or in the other scan field (102-8). This selective scanning in one or the other of the posssible scan fields avoids the necessity of scanning patterns within the boundary using two different scan fields. It has been found that when patterns having critical dimensions are scanned by two different scan fields, that is, partially in one scan field and partially in another scan field, substantial errors are frequently introduced.

In accordance with the present invention, such errors can be reduced or eliminated by wholly scanning critical dimensions in the boundary region using only one of the two possible scan fields.

In FIG. 7, if the width of the partition, W7, is 401.5 microns and the scan field 102-7 is 512 microns, the portion of the boundary B1 is 55.5 microns and the full boundary region demension B2 is 110.5 microns. In a similar manner, a portion of the boundary region having dimension B3 lies between partitions 106-7 and 106-5 and measures 31 microns. The full boundary between scan field 102-6 (not shown) and the scan field 102-7 is then 62 microns wide.

Chip Pattern -- FIG. 8

In FIG. 8, a chip area 105 is shown including a chip pattern 107. The chip pattern 107 is to be exposed with an electron beam in accordance with the present invention. The pattern includes a number of pads 131 which are identified as P1, P2, . . . , P24. The pads are generally arranged around the perimeter of the chip area 105. The pads 131 are utilized, for example, to form off-chip connections in a final package integrated circuit (not shown). The pads 131 and other areas on the chip area 105 include various lines 132. In FIG. 8, the lines all represent conductors in one layer of a multi-layer semiconductor structure. The present invention, of course, also pertains to other layers in which the chip patterns represent semiconductor regions and other circuit elements well known in the field of integrated circuits.

The chip pattern 107 is layed out for convenience in connection with an X axis and a Y axis which intersect at an origin 130. Each line 132 and each pad 131 in the circuit pattern 107 is initially specified in accordance with its position and size relative to the origin 130. Furthermore, each portion of the chip pattern 107 is formed by one or more different sized shapes. While many different shapes can be employed, the particular example of FIG. 8 employs rectangular shapes. Each rectangular shape, is designated by four numbers which represent its displacement along the X axis from the origin 130, its displacement along the Y axis from the origin 130, its length along the X axis, and its length along the Y axis. These four numbers are designated as four words, namely, WORD 1, WORD 2, WORD 3, and WORD 4, respectively. The words are conveniently stored and processed in the data processing apparatus of FIG. 1.

By way of example, and referring to FIG. 8, the P12 pad 131 is a rectangle which measures 120 microns by 120 microns or 240 by 240 one-half microns. In FIG. 8, the coordinate system is measured in one-half microns (because the electron beam spot diameter is one-half micron wide). Therefore, as indicated in FIG. 8, the dimensions of the P12 pad 131 are 240 by 240 one-half microns.

The displacement of the P12 pad 131 from the origin 130 is 1,280 one-half microns along the X axis and -1,120 one-half microns along the Y axis. Hence the displacement address from origin 130 is designated as [1,280, -1,120]. The displacement address designates the location of the lower left-hand corner of the P12 pad 131. The P12 pad 131 has a length along the X axis of 240 one-half microns and a length along the Y axis of 240 one-half microns.

In accordance with the four word notation, the WORD 1, WORD 2, WORD 3 and WORD 4 designations which specify the rectangular shape for the P12 pad 131 are 1,280, -1,120, 240, 240, respectively.

The P12 pad 131 has a rectangle 133 adjacent to its left-hand edge. The WORD 1, WORD 2, WORD 3 and WORD 4 designations for the rectangle 133 are 1,260, -1,040, 20 and 80.

In a similar manner, the P11 pad 131 has the WORD 1 through WORD 4 designations 1,280, -720, 240, 240, respectively.

In FIG. 8, every portion of the chip pattern 107 is specified in terms of its rectangular dimensions and its offset position from the origin 130. A file listing for the entire chip pattern 107 of FIG. 8 appears as TABLE I at the end of this specification. Referring to TABLE I, the record number (RECORD NO.) column identifies each 4-word record. As previously explained, WORD 1 designates the X axis offset from the origin 130. WORD 2 designates the Y axis offset from the origin 130. WORD 3 designates the length, XL, of the rectangle along the X axis. WORD 4 designates the length, YL, of the rectangle along the Y axis. Certain of the records of TABLE I designate header information to identify TABLE I.

Specifically, referring to record numbers 1 and 2 the four words merely indicate information identifying TABLE I and its use in connection with other integrated circuit layers.

Record number 3 is a header which indicates in WORD 1 and WORD 2 that the size of the chip area is 1,606 microns in the X axis and 1,350 microns in the Y axis. WORD 4 indicates that the remainder of TABLE I is comprised of 681 record numbers, that is, record numbers 4 through 684.

Record number 4 specifies the four words which define the P12 pad 131 as previously described.

Record number 5 specifies rectangle 133 in the manner previously described.

Record number 6 describes the P11 pad 131 in the manner previously described.

Additionally, record numbers 8, 10, 12, . . . , 24, 26, 28, 30, . . . , 48, 50, designate the pads P10, P9, P8, . . . , P2, P1, P24, P23, . . . , P14, P13, respectively. In a similar manner, every other rectangular shape on the chip pattern within chip area 105 is defined by a four word record entry in TABLE I.

By way of further example, still referring to FIG. 8 and TABLE I, record number 331 specifies the land (for a via hole) V2. Record 333 specifies the land V1. Record 374 specifies the land V3 and record 375 specifies the land V4. Record 377 specifies the line L1, record 426 specifies the line L3, record 430 specifies the line L4 and record 441 specifies the line L2. The lines L1 through L4 and the via holes V1 through V4 lie in the general vicinity of a partition line 120(7/8) which has been drawn to partition the chip pattern on the chip area 105 of FIG. 8. It should be noted, however, that the input file of TABLE I has entries with respect to the origin 130 without regard to any partitioning of the chip area 105.

The chip pattern of FIG. 8 is divided into 12 partitions 106-1 through 106-12 in the manner described previously in connection with FIG. 7. Accordingly, the data of the unpartitioned file of TABLE I must be processed to partition the data so that it corresponds with the partitions 106-1 through 106-12 of FIG. 8. Actually, the partitions 106-11 and 106-12 do not contain any of the chip pattern and hence only 10 partitions need be employed to define the chip pattern of the chip area 105 in FIG. 8.

Referring to FIG. 8, the partitioning of the chip pattern 107 requires that portion of the chip pattern in each of the partitions 106 to have its data in TABLE I translated relative to the XY axes having an origin 130 to a new coordinate system having an origin in the lower lefthand corner of the scan field 102 associated with the particular partition 106. Referring to FIG. 7, the origin 130 is shifted to a point 134-7 in connection with the partition 106-7. The point 134-7 is the lower left-hand corner of the scan field 102-7.

Referring to FIG. 8, the partitions 106-1 has a translated coordinate system including the X1 axis and the Y1 axis which intersect at the origin 134-1. The origin 134-1 is 1412 one-half microns shifted down from the X axis and 1716 one-half microns shifted over from the Y axis. The 1412 one-half micron value is determined in the following manner. The shift from the X axis is equal to one-half the height of partition 106-5 (equal to 450 one-half microns), the total height of the partition 106-1 (900 one-half microns) plus the width of the boundary of the partition 106-1 and the scan field 102-1 (62 one-half microns). Similarly the 1,716 number is equal to the width of the partitions 106-1 and 106-2 (each 803 one-half microns) plus the width of the boundary between the scan field 102-1 and the partition 106-1 (110 one-half microns). All of the chip pattern rectangular shapes of FIG. 8 which fall within the partition 106-1 may have their coordinates translated to the new axis by adding 1,716 to the X axis coordinate and by adding 1,412 to the Y axis coordinate. In general, this translation involves searching all of the records in the TABLE I file to ascertain which ones fall within the scan field associated with the partition 106-1 of FIG. 8. Thereafter the X axis and Y axis translation factors are added to form the translated coordinates. Such a translation for all the rectangular shapes and all the partitions of FIG. 8 are shown in TABLE II.

Referring to TABLE II, record numbers 1 and 2 merely specify information identifying the table and its use in forming an integrated circuit. WORD 2 of record number 2 indicates that TABLE II comprises the following 733 record numbers, namely, record numbers 3 through 735.

Record number 3 indicates that the table specifies a chip pattern which measures 1,606 by 1,350 microns.

Record number 4 indicates the number of one-half microns that the table 24 of FIG. 1 must be moved from the origin 130 in order to superimpose the scan field 102 of the electron beam over the partition 106. The table is moved -1,204 one-half microns in the X direction and -900 one-half microns in the Y direction so that the scan field has its translated center at 130-1 and has its lower left-hand corner at point 134-1 as shown in FIG. 8.

Record number 5 of TABLE II indicates that the partition 106-1 has a width in the X direction of 803 one-half microns and in the Y direction of 900 one-half microns. WORD 4 of record number 5 indicates that the partition 106-1 is defined by 8 rectangles. Those 8 rectangles are specified in the following 8 record numbers, namely 6 through 13.

Record number 6 defines the P20 pad 131 with respect to the X1 Y1 coordinate system. Record number 6 indicates that the lower left-hand corner of the P20 pad 131 has a location which is 196 one-half microns along the X axis and 692 one-half microns along the Y1 axis all with respect to the origin 131-1. The WORD 3 and WORD 4 entries of TABLE II are identical to the WORD 3 and WORD 4 entries of TABLE I since no change in the size of the rectangle has been implemented with respect to the translation presently described. Of course, if a change in scale were desired, the WORD 3 and WORD 4 entries could be also translated to changed values.

Record number 6 in TABLE II corresponds to record number 36 in TABLE I. The TABLE II entry of 196 is obtained by adding 1,716 to -1,520. The 692 TABLE II entry is obtained by adding 1,412 to -720 in the manner previously described.

In TABLE II, the records 8 and 10 specify the P19 and P18 pads 131. The records 8 and 10 of TABLE II correspond to the records 38 and 40 of TABLE I.

In TABLE II, record 14 specifies the amount that the table 24 of FIG. 1 must be moved from its position at partition 106-1 in order to position the scan field 102 over the partition 106-2. The move is 803 one-half microns in the positive X direction and no movement in the Y direction.

Record 14 specifies the size of the partition 106-2, namely 803 by 900 one-half microns. WORD 4 specifies the number of record entries and hence the number of rectangular shapes which form the pattern within the partition 106-2. The number of rectangular shapes is 9 and includes records 16 through 24.

In TABLE II, record 25 indicates the 803 one-half microns required to move the scan field from its position at partition 106-2 to superposition it over the partition 106-3. Record 26 indicates the 803 by 900 one-half micron size and that 139 rectangular shapes are employed to define the chip pattern within the partition.

The 139 shapes are defined in the records 27 through 165.

In TABLE II, record 166 specifies an 803 one-half micron move from its position at partition 106-3 to superposition the scan field 102 over the partition 106-4 of FIG. 8.

Record number 167 indicates the partition size and that 112 record numbers are employed to define the chip pattern within the partition 106-4. Those 112 record numbers are 168 through 279.

Record number 280 specifies the zero X axis and 900 Y axis movement of the table 24 of FIG. 1 from its position at partition 106-4 to superimpose the scan field 102 over the partition 106-5 of FIG. 8.

Record number 281 indicates the size of the partition and that six record numbers are employed to define the partition. The record numbers are 282 through 287.

Record number 288 specifies the -2,409 one-half micron X axis move of the table 24 of FIG. 1 from its position at partition 106-5 to superimpose the scan field 102 over the partition 106-6 of FIG. 8.

Record number 289 specifies the size of the partition and that six records comprising record numbers 290 through 295 that define the chip pattern.

Record number 296 specifies the movement of the table 24 from its position at partition 106-6 to superimpose the scan field 102 over the partition 106-7 of FIG. 8. Record number 297 indicates the 109 record numbers running from record number 298 through record number 406 which define the chip pattern within the partition. The L1, L2, 3, V1, V3, and V4 shapes in FIG. 8 are defined in TABLE II by record numbers 367, 402, 393, 342, 364, 365, respectively, and the corresponding record numbers in TABLE I are 377, 441, 426, 333, 374, 375, respectively. These record numbers will be utilized hereinafter in accordance with the double boundary partitioning of the present invention since they define shapes which fall on the partition boundary 120 (7/8) between partition 106-7 and partition 106-8.

In TABLE II, record number 407 specifies the 803 one-half micron move of table 24 from its position at partition 106-7 in order to superimpose the scan field 102 over the partition 106-8 of FIG. 8.

Record number 408 among other things specifies that the chip pattern within the partition 106-8 includes 190 records which run from record number 409 to record number 598.

In connection with partition 106-8, the patterns L2, L3, V1, V3 and V4 do not find a record entry even though part of those patterns appear in partition 106-8. The reason they do not appear in the records for partition 106-8 is because, in accordance with the present invention, the entire designation for those patterns appears in the record for partition 106-7. Note in connection with the record for partition 106-8 that a portion of the pattern L3 is stored in record 592 and the entire pattern for V2 is stored in record 549.

Record number 599 of TABLE II indicates the 803 one-half micron X axis movement of the table 24 required from its position at partition 106-8 to superimpose the scan field 102 over the partition 106-9 of FIG. 8.

Record number 600 indicates that 117 record numbers, which appear as record numbers 601 through 717 are required to designate the chip pattern falling within the partition.

Record number 718 of TABLE II specifies the 803 one-half micron movement required from the position at partition 106-9 to superimpose the scan field 102 over the partition 106-10 of FIG. 8. Record number 719 indicates that 14 records, appearing in record numbers 720 through 724, are required to designate the chip pattern falling within the partition 106-10.

Record number 734 designates a move to return the scan field to the origin 130 and record number 735 indicates the end of the TABLE II listing.

Partition Boundary--FIG. 9

In FIG. 9, an expanded view of the chip pattern in the partitions 106-7 and 106-8 in the vicinity of the partition boundary 120(7/8) is shown. In FIG. 9, the lines which cross the partition boundary 120(7/8) are designated as L1, L2, ..., L8. Similarly, the land patterns which cross the boundary 120(7/8) are designated as V1, V2, ..., V6. If the patterns L1 thorugh L8 and V1 through V6 were scanned directly, then a portion of each would be exposed by an electron beam in connection with the partition 106-7 and also a portion in connection with the partition 106-8. For example, line L1 would be exposed four-fifths in connection with partition 106-7 and one-fifth in connection with partition 106-8. Any error in the movement of the table 24 of FIG. 1 in positioning the scan field 102 in connection with the partition 106-7 relative to the partition 106-8 would tend to alter the dimensions of the line L1. Line L1 is, in the particular example, intended to be 5 microns wide. An unwanted change in the relative position of the scan fields would tend to either divide the line L1 into two lines or to reduce the dimensions of the line. Errors of this type, particularly when the chip pattern being formed are critical dimensions, such as regions of transitors or other semiconductor devices, tend to introduce significant errors. In accordance with the present invention, this problem is avoided at scan boundary regions by selectively including shapes having critical dimensions all within one partition or all within another partition. For example, the line L1 in FIG. 9 is totally exposed in connection with the processing of the partition 106-7 and is not exposed at all in connection with the scanning of the partition 106-8. Further details of the scanning at the partition boundary are described in connection with FIGS. 10 and 11.

Double Boundary Partitioning--FIGS. 10 & 11

In FIG. 10, the portion of the chip pattern 107 scanned within the scan field 102-7 in connection with the partition 106-7 is shown. A detailed listing of the rectangles which comprise the chip pattern of FIG. 10 appears in TABLE II in record numbers 297 through 406. In a similar manner, FIG. 11 depicts that portion of the chip pattern 107 which is scanned within the scan field 102-8 in connection with the partition 106-8. For convenience, the partition line 120(7/8) in FIG. 8 has been separated in FIGS. 10 and 11 and appears therein as lines 120(7) and 120(8), respectively. In the actual scanning, however, the lines 120(7) and 120(8) are superimposed and form only one common boundary line 120(7/8) as shown in FIG. 8.

Referring to the boundary 120(7) in FIG. 10, it can be noted that the patterns V5, V3, L1, V4, L2, V1, L7, and V6 all extend across the boundary 120(7) into the region between the boundary 120(7) and the outer perimeter of the scan field 102-7. Because the area of the scan field 102-7 intentionally is greater than the area of the partition 106-7, the extension into the boundary region of the portions of the pattern along the boundary 120(7) is readily facilitated in accordance with the present invention.

Referring to FIG. 11 by way of contrast, no portion of the chip patterns V5, V3, L1, V4, L2, V1, L7, and V6 appear in FIG. 11 since all portions of those chip patterns are included in FIG. 10.

Chip Pattern Partitioning

The decision of where to position shapes (rectangles) falling on the boundary or in more than one partition area can be made manually by inspection of FIGS. 8 and 9. Since the coordinates of all the rectangles are available in TABLE I, the partitioning can be performed automatically with greater speed using data processing equipment.

One preferred method of partitioning a chip pattern using data processing techniques will now be described.

It is assumed that the TABLE I data is stored in the data processing system and it is identified as the unpartitioned file. A decision is made as to how many partitions into which the pattern represented by the TABLE I file is to be divided. In accordance with the present example, 12 different partitions, of which only 10 contain any information, are to be formed.

The partitions, as can be seen in connection with FIG. 12, are arrayed in rows and columns. The first column, designated as 01, includes the partitions 106-1, 106-6 and 106-7. The second column, designated as 0, includes the partitions 106-2, 106-11 and 106-8. The next column, designated as +1, includes the partitions 106-3, 106-12 and 106-9. The final column, designated as +2, includes the partitions 106-4, 106-5 and 106-10.

In a similar manner, the rows of partitions can be observed with respect to FIG. 12. The row designated as 0 includes the partitions 106-1, 106-2, 106-3 and 106-4. The row designated as +1 includes the partitions 106-6, 106-11, 106-12 and 106-5. The row designated as +2 includes the partitions 106-7, 106-8, 106-9 and 106-10.

In TABLE I, record numbers 1 and 2 are accessed from the unpartitioned file and stored in record number 1 and 2 locations of the partitioned file which is TABLE II. This information merely serves to identify the pattern. The TABLE I information only represents one pattern layer while any given circuit design typically has a number of layers. Each layer, however, is similar to the layer represented in TABLE I and would be processed in the manner now to be described for TABLE I.

Initially, the first shape (the rectangle of record number 4) is accessed from the unpartitioned file. After the first shape is processed, then the second shape (record number 5) is accessed and processed in the manner not to be described until all shapes, 681 in all for TABLE I, have been processed.

Record number 4 as accessed from TABLE I has coordinates established with respect to the origin 130 (see FIG. 8). The first step is to shift the origin to a new origin 130' which is on both an X and Y partition boundary. The shift is carried out by adding -450 one-half microns to the Y coordinate of record number 4. No X axis addition is required since origin 130 is already on an X axis partition boundary.

The next step in the process of dividing the whole pattern of FIG. 8 into twelve partitions is to determine the partitions that the shape currently being processed falls into. The process for each shape first examines the coordinates in the X direction to determine the first and last partition columns which the shape falls into. This determination is carried out initially for the X axis by executing the subroutine of CHART I.

The details of the steps in CHART I will be explained hereinafter in connection with the examples of FIG. 12. Briefly, however, each shape is analyzed in the X direction for determination of whether or not the shape has any portions in each of the columns, starting with the FIRST and going to the LAST column. The partitioning is done by using a four-word quantity defined as the RESIDUAL COLUMN SHAPE. Initially, the RESIDUAL COLUMN SHAPE includes the entire shape as defined by the four words (WORD 1, ..., WORD 4) from the TABLE I record. When the partitioning of the FIRST column occurs, the portion of the shape within the FIRST column (again designated by four words) is placed in a local storage area with a column identification code appended. The portion placed in the local storage area is designated as the COLUMN SHAPE and it is subtracted from the RESIDUAL COLUMN SHAPE. Thereafter, the COLUMN SHAPE for the next column after the FIRST is stored in a local storage area with appropriate column identification, and the COLUMN SHAPE thus stored is subtracted from the RESIDUAL COLUMN SHAPE. Processing continues in this manner for each column until the LAST column is reached. When the LAST column is reached, the balance of the RESIDUAL COLUMN SHAPE is stored in the local storage area with appropriate identification of the LAST column. Under certain conditions, of course, as discussed in connection with CHART I, the FIRST column is equal to the LAST column and the particular shape is entirely within a single column.

After all of the COLUMN SHAPES have been stored in local storage (four words each) with appropriate identification of the column, each COLUMN SHAPE is then further processed along the Y axis to determine the portion, called the ROW/COL SHAPE, of each COLUMN SHAPE which is located in each row.

In scanning in the Y direction, the steps of CHART I are again repeated for each COLUMN SHAPE in local storage. In accordance with that CHART I, the FIRST and LAST rows are determined for a first one of the COLUMN SHAPES. Each stored COLUMN SHAPE initially forms one RESIDUAL ROW/COL SHAPE. This RESIDUAL ROW/COL SHAPE is then processed from the FIRST to the LAST row. As each row is processed, a ROW/COL SHAPE is formed and is subtracted from the RESIDUAL ROW/COL SHAPE. The ROW/COL SHAPE thus formed is stored in local storage with appropriate row identification appended to the column identification. Each ROW/COL SHAPE thus formed has, therefore, an appropriate row and column identification which uniquely defines one of the partitions into which the ROW/COL SHAPE is to be placed.

With the ROW/COL SHAPE thus having a unique one of the partitions identified, it now becomes a task of translating the coordinates for the X and Y origins of that ROW/COL SHAPE to appropriate values associated with an origin of the identical portion. The X and Y coordinates currently stored in WORD 1 and WORD 2 are with respect to the origin 130'. The coordinates for the lower left hand corner of the partition to which the portion of the shape is to be assigned are subtracted from the WORD 1 and WORD 2 values of the ROW/COL SHAPE in local storage. The new WORD 1 and WORD 2 result is a shift of the origin from 130' to the lower left hand corner of the identified partition. Next, the X and Y offset values (OFST in CHART I) are added to the new WORD values. In the present example, the X axis offset added is 111 one-half microns and the Y axis offset added is 31 one-half microns. The result of adding the offset values translates the origin from the lower left hand corner of the identified partition to the lower left hand corner of the scan field associated with that partition.

When all of the rows have been thus processed for a particular COLUMN SHAPE, then the processing is again repeated for the next COLUMN SHAPE in turn storing each new ROW/COL SHAPE with a row and column identification and translated coordinates. Finally, when all of the COLUMN SHAPES have been thus processed, processing for a single one of the TABLE record number shapes is complete and the system is now ready to repeat the process all over again for the next record number shape. In the example of TABLE I, the first shape is record number 4 and is the next shape is record number 5. When the processing for record number 5 is complete, the processing continues for each of the shapes of record numbers 6 through 685 of TABLE I.

After all of the shapes of TABLE I have been processed and stored in a local store with appropriate row and column identifications, the ROW/COL SHAPES are then sorted by partition and listed in the partitioned file which appears as TABLE II.

Further details of CHART I will not be explained. CHART I is essentailly a FORTRAN subroutine which is executed a multiple number of times for each shape. The subroutine automatically allocates portions of shapes to positions including those portions lying in the overlapping boundary regions between adjacent scan areas.

    __________________________________________________________________________     CHART I                                                                        __________________________________________________________________________     S1   SUBROUTINE PBND (FIRST, LAST, OFST, PLEN, ORGN, LEN)                      S2   INTEGER FIRST, LAST, PLEN, ORGN, LEN, OVER, UNDER, OFST                   S3 C                                                                           S4 C THIS ROUTINE DETERMINES THE SPREAD OF FIELDS A                            S5 C RECTANGLE MAY COVER. ONE AXIS AT A TIME                                   S6 C                                                                           S7   FIRST=ORGN/PLEN+1                                                         S8   IF(ORGIN.LT.0)FIRST=(ORGN+1)/PLEN                                         S9   NXT=ORGN+LEN                                                              S10  LAST=NXT/PLEN+1                                                           S11  IF(NXT.LT.0)LAST=(NXT+1)/PLEN                                             S12  UNDER=FIRST*PLEN-ORGN                                                     S13  OVER=NXT-PLEN*(LAST-1)                                                    S14                                                                               C                                                                           S15                                                                               C CHECK FOR POSSIBLE EXTENDED FIELD COVERAGE TO                             S16                                                                               C MINIMIZE THE NUMBER OF FIELDS THIS RECTANGLE MUST                         S17                                                                               C COVER                                                                     S18  IF(FIRST.EQ.LAST)GO TO 30                                                 S19  IF(UNDER.LT.OFST)FIRST=FIRST+1                                            S20  IF(OVER.LT.OFST)LAST=LAST-1                                               S21  IF(FIRST.LE.LAST)GO TO 30                                                 S22  IF(OVER-UNDER)10,10,20                                                    S23  10 FIRST=LAST                                                             S24  GO TO 30                                                                  S25  20 LAST=FIRST                                                             S26  30 RETURN                                                                 S27  END                                                                       __________________________________________________________________________

In CHART I, statement S1, the subroutine is named as partition boundary (PBND) and the input values for the variables indicated, FIRST, LAST, OFST, PLEN, ORGN, and LEN are called for. FIRST and LAST are initially 0. OFST is the value of the offset which is equal to the width of the boundary region, B2 in FIG. 7, between the partition boundary line 120 and the scan field perimeter 102. In the particular example of FIG. 8, OFST is equal to 110 one-half microns for X axis scans or 31 one-half microns for Y axis scans. The quantity PLEN is equal to the partition width which, in the example of FIG. 8 is 803 one-half microns for X axis scans or 900 one-half microns for Y axis scans.

The quantity ORGN designates the origin of each particular shape with respect to the axis of scan, either X or Y. The quantity LEN is equal to the length of each particular shape in the direction of scan.

Statement S2 incidates that the values of statement S1 are integers. The quantity OVER designates the length that a shape extends from the partition boundary line in the partition in which the shape terminates. The quantity UNDER designates the length between the beginning of the shape and the first partition boundary line.

Statement S3 through S6 are reserved for a textual comment which help explain CHART I.

In Statement S7, the quantity FIRST is calculated from given values of ORGN and PLEN. Referring to FIG. 12, an example of the S7 calculation is described in connection with the X axis scan of rectangular shape 141. In FIG. 12, the partitions running along the X axis are 106-1, 106-2, 106-3 and 106-4 in connection with the Y coordinate in the vicinity of the shape 141. The partition boundary line 122/3 is the 0 axis. Coordinates to the right of the 0 axis are positive and to the left are negative. Since the coordinate for ORGN will be less than the length of a full partition, PLEN, the ratio ORGN/PLEN is a fraction less than 1. The integer value for FIRST in S7 will therefore be 1. The quantity FIRST is indicated as being at the partition boundary line 120(3/4) in FIG. 12.

In statement S8, calculations are made for values in X of ORGN less than 0. Since ORGN is positive and hence greater than 0 for the shape 141, S8 is not employed. Another example in which the ORGN has a negative X coordinate is the shape 142. For the shape 142, the FIRST value becomes a -1 which is indicated as being at the partition boundary line 120(1/2).

In statement S9, the value of NXT is calculated by summing the ORGN and LEN values. In connection with the shape 141, the NXT value falls within the positive region between 0 and +1.

In statement S10, the value of LAST is calculated for positive values of NXT. As shown in FIG. 12, the value of LAST for the shape of 141 is 1 and hence also falls on the boundary line 120(3/4).

Statement S11 is used for negative values of NXT. None of the examples in FIG. 12 has a negative NXT, however, the calculation is analogous to that of statement S8 for negative values of ORGN.

In statement S12, UNDER is calculated based upon the previous calculations of FIRST and LAST and NXT. The various quantities calculated for UNDER and OVER for the shapes 141 through 145 in FIG. 12 are appropriately labeled.

The manner in which these calculations are employed in order to make a determination to which partition column or columns a particular shape is to be allocated are now described in connection with the statements S18 through S26. The statements S14 through S17 are merely for textual comments describing the program.

In statement S18, if FIRST is equal to LAST, then a decision as to which partition column is to receive the COLUMN SHAPE has been made since the shape fits entirely within the column designated by the quantity FIRST. An example where FIRST equals LAST is shape 141. The value of FIRST is +1 and designates the column containing partition 106-3. The X axis processing of shape 141 is then complete. The COLUMN SHAPE in this example includes the original four words for the shape 141 and has the column +1 identification appended as previously described.

In statement S19, the condition of UNDER being less than OFST is examined. Such a condition occurs, for example, both in connection with the shapes 143 and 144. In those conditions, the value of FIRST is changed to equal FIRST +1. That is, the change is from a -1 to 0 thereby changing the designation from the boundary line 120(7/8) to the boundary line 120(8/9). The effect of this change is to place those portions of the shape to the left of boundary line 120(7/8) [but still within the scan field 10(2-8) within the COLUMN SHAPE for the -1 column which contains the partition 106-8. Thereafter that COLUMN SHAPE is subtracted leaving the RESIDUAL COLUMN shape as everything to the right of boundary 120(8/9)].

In statement S20, an examination is made to determine whether OVER is less than OFST. If that condition exists, the value of LAST is set equal to LAST -1. The condition of S20 is not met in connection with the shape 143 so that LAST remains a +1 indicated at the boundary 120(9/10). The result is that the RESIDUAL COLUMN SHAPE [that is, everything to the right of boundary 120(8/9)] is stored as the COLUMN SHAPE for the +1 column containing partition 106-9. In connection with the shape 144, however, OVER is less than OFST, so that LAST is set equal to LAST -1. In connection with the shape 144, therefore, LAST is changed from +1 to 0, that is, from the boundary line 120(9/10) to the boundary line 120(8/9). The result is that the entire shape 144 is stored as the COLUMN SHAPE for the -1 column containing partition 106-8.

In statement S21, the new values of FIRST and LAST as they may have been changed in S19 and S20 are examined. If FIRST is less than or equal to LAST, then a determination has been made as to the partition allocation. In connection with the shape 144, FIRST, now equal to 0, is equal to LAST now also equal to 0. The 0 value for FIRST therefore designates that the partition 106-8 is the one to receive the entire shape 144.

In statement S22, a comparison of OVER and UNDER is made under the condition that FIRST was greater than LAST in S21. Under the condition that UNDER was greater than OVER, S22 would proceed to S23. No example of such a condition is shown in FIG. 12. In FIG. 12, however, the value of OVER is greater than UNDER in connection with shape 145 so that S22 branches to S25 and LAST is set equal to FIRST. In connection with shape 145, FIRST was already set to +2, in connection with S19. Therefore, LAST becomes set equal to +2 in S25. The meaning is in S25 that the shape 145 can be scanned entirely in one partition. The shape 145 is therefore not divided along the boundary 120(12/5) but is scanned entirely within the partition 106-5. The above method places shape 145 in the partition that shape 145 would be most centrally located within.

While the invention has been particularly shown and described with reference to the preferred embodiments thereof, it will be understood by those skilled in the art that those changes in form and details may be made therein without departing from the spirit and the scope of the invention.

                                      TABLE I                                      __________________________________________________________________________           WORD WORD WORD WORD       WORD WORD WORD WORD                            RECORD                                                                               1    2    3    4    RECORD                                                                               1    2    3    4                               NO.   X    Y    XL   YL   NO.   X    Y    XL   YL                              __________________________________________________________________________     1     1    5    685  1    61    -905 913  10   30                              2     3    682  0    70   62    -745 913  10   30                              3     1606 1350 0    681  63    -617 913  10   30                              4     1280 -1120                                                                               240  240  64    -521 913  10   30                              5     1260 -1040                                                                               20   80   65    -1191                                                                               815  1574 10                              6     1280 -720 240  240  66    -1193                                                                               697  10   126                             7     1260 -640 20   80   67    -1191                                                                               695  1574 10                              8     1280 -320 240  240  68    -585 697  10   126                             9     1260 -240 20   80   69    -393 697  10   126                             10    1280 80   240  240  70    341  573  14   14                              11    1260 160  20   80   71    341  693  14   14                              12    1280 480  240  240  72    309  669  14   14                              13    1260 560  20   80   73    309  621  14   14                              14    1280 880  240  240  74    311  625  10   54                              15    1260 960  20   80   75    271  645  14   14                              16    880  1080 240  240  76    277  573  14   14                              17    960  1060 80   20   77    277  693  14   14                              18    480  1080 240  240  78    245  621  14   14                              19    560  1060 80   20   79    213  573  14   14                              20    80   1080 240  240  80    213  669  14   14                              21    160  1060 80   20   81    217  623  36   10                              22    -320 1080 240  240  82    215  625  10   54                              23    -240 1060 80   20   83    175  645  14   14                              24    -720 1080 240  240  84    181  573  14   14                              25    -640 1060 80   20   85    181  693  14   14                              26    -1120                                                                               1080 240  240  86    149  669  14   14                              27    -1040                                                                               1060 80   20   87    149  621  14   14                              28    -1520                                                                               880  240  240  88    151  625  10   54                              29    -1280                                                                               960  20   80   89    185  647  38   10                              30    -1520                                                                               480  240  240  90    111  645  14   14                              31    -1280                                                                               560  20   80   91    117  573  14   14                              32    -1520                                                                               80   240  240  92    117  693  14   14                              33    -1280                                                                               160  20   80   93    85   669  14   14                              34    -1520                                                                               -320 240  94   240   94   621  14   14                              35    -1280                                                                               -240 20   80   95    87   625  10   54                              36    -1520                                                                               -720 240  240  96    121  647  38   10                              37    -1280                                                                               -640 20   80   97    47   645  14   14                              38    -1520                                                                               -1120                                                                               240  240  98    53   573  14   14                              39    -1280                                                                               -1040                                                                               20   80   99    53   693  14   14                              40    - 1120                                                                              -1320                                                                               240  240  100   21   669  14   14                              41    -1040                                                                               -1080                                                                               80   20   101   21   621  14   14                              42    -720 -1320                                                                               240  240  102   23   625  10   54                              43    -640 -1080                                                                               80   20   103   57   647  38   10                              44    -320 -1320                                                                               240  240  104   -17  645  14   14                              45    -240 -1080                                                                               80   20   105   -11  573  14   14                              46    80   -1320                                                                               240  240  106   -11  693  14   14                              47    160  -1080                                                                               80   20   107   -43  669  14   14                              48    480  -1320                                                                               240  240  108   -43  621  14   14                              49    560  -1080                                                                               80   20   109   -41  625  10   54                              50    880  -1320                                                                               240  240  110   -7   647  38   10                              51    960  -1080                                                                               80   20   111   -81  645  14   14                              52    366  696  28   128  112   -75  573  14   14                              53    -1260                                                                               575  40   370  113   -75  693  14   14                              54    376  812  20   216  114   -107 669  14   14                              55    -208 1010 602  20   115   -107 621  14   14                              56    -210 1012 20   76   116   -105 625  10   54                              57    -1223                                                                               575  1574 10   117   -71  647  38   10                              58    -1223                                                                               935  1478 10   118   -145 645  14   14                              59    -393 913  10   30   119   -139 573  14   14                              60    -1223                                                                               911  838  10   120   -139 693  14   14                              121   -171 669  14   14   181   -299 885  14   14                              122   -171 621  14   14   182   -297 841  10   54                              123   -169 625  10   54   183   -261 861  14   14                              124   -135 647  38   10   184   -267 933  14   14                              125   -209 645  14   14   185   -267 813  14   14                              126   -203 573  14   14   186   - 235                                                                               837  14   14                              127   -203 693  14   14   187   -235 885  14   14                              128   -235 669  14   14   188   -233 841  10   54                              129   -235 621  14   14   189   -295 863  38   10                              130   -233 625  10   54   190   -197 861  14   14                              131   -199 647  38   10   191   -203 933  14   14                              132   -273 645  14   14   192   -203 813  14   14                              133   -267 573  14   14   193   -171 837  14   14                              134   -267 693  14   14   194   -171 885  14   14                              135   -299 669  14   14   195   -169 841  10   54                              136   -299 621  14   14   196   -231 863  38   10                              137   -297 625  10   54   197   -133 861  14   14                              138   -263 647  38   10   198   -139 933  14   14                              139   -337 645  14   14   199   -139 813  14   14                              140   -331 573  14   14   200   -107 837  14   14                              141   -331 693  14   14   201   -107 885  14   14                              142   -363 669  14   14   202   -105 841  10   54                              143   -363 621  14   14   203   -167 863  38   10                              144   -361 625  10   54   204   -69  861  14   14                              145   -327 647  38   10   205   -75  933  14   14                              146   -401 645  14   14   206   -75  813  14   14                              147   -395 573  14   14   207   -43  837  14   14                              148   -395 693  14   14   208   -43  885  14   14                              149   -427 669  14   14   209   -41  841  10   54                              150   -427 621  14   14   210   -103 863  38   10                              151   -425 625  10   54   211   -5   861  14   14                              152   -391 647  38   10   212   -11  933  14   14                              153   -465 645  14   14   213   -11  813  14   14                              154   -459 573  14   14   214   21   837  14   14                              155   -459 693  14   14   215   21   885  14   14                              156   -491 669  14   14   216   23   841  10   54                              157   -491 621  14   14   217   -39  863  38   10                              158   -489 625  10   54   218   59   861  14   14                              159   -455 647  38   10   219   53   933  14   14                              160   -523 573  14   14   220   53   813  14   14                              161   -523 693  14   14   221   85   837  14   14                              162   -555 669  14   14   222   85   885  14   14                              163   -555 621  14   14   223   87   841  10   54                              164   -553 625  10   54   224   25   863  38   10                              165   -523 933  14   14   225   123  861  14   14                              166   -459 933  14   14   226   117  933  14   14                              167   -395 933  14   14   227   117  813  14   14                              168   -395 813  14   14   228   149  837  14   14                              169   -459 813  14   14   229   149  885  14   14                              170   -523 813  14   14   230   151  841  10   54                              171   -491 885  14   14   231   89   863  38   10                              172   -491 837  14   14   232   187  861  14   14                              173   -427 885  14   14   233   181  933  14   14                              174   -427 837  14   14   234   181  813  14   14                              175   -487 887  70   10   235   213  837  14   14                              176   -425 841  10   54   236   213  885  14   14                              177   -487 839  70   10   237   215  841  10   54                              178   -331 933  14   14   238   153  863  38   10                              179   -331 813  14   14   239   245  933  14   14                              180   -299 837  14   14   240   245  813  14   14                              241   277  837  14   14   301   169  1055 34   10                              242   277  885  14   14   302   -1195                                                                               621  14   14                              243   279  841  10   54   303   -1163                                                                               621  14   14                              244   309  885  14   14   304   -1163                                                                               669  14   14                              245   341  885  14   14   305   -1195                                                                               669  14   14                              246   341  837  14   14   306   -1193                                                                               625  10   54                              247   309  837  14   14   307   -1161                                                                               625  10   54                              248   311  841  10   54   308   -1125                                                                               645  14   14                              249   343  841  10   54   309   -1131                                                                               573  14   14                              250   325  525  14   14   310   -1131                                                                               693  14   14                              251   413  1005 14   14   311   -1099                                                                               621  14   14                              252   349  981  14   14   312   -1067                                                                               573  14   14                              253   309  981  14   14   313   -1067                                                                               669  14   14                              254   261  1045 14   14   314   -1095                                                                               623  38   10                              255   229  765  14   14   315   -1065                                                                               625  10   54                              256   -315 765  14   14   316   -1029                                                                               645  14   14                              257   -507 765  14   14   317   -1035                                                                               573  14   14                              258   169  981  14   14   318   -1035                                                                               693  14   14                              259   161  981  14   14   319   -1003                                                                               669  14   14                              260   169  1045 14   14   320   -1003                                                                               621  14   14                              261   161  1045 14   14   321   -971 621  14   14                              262   -363 717  14   14   322   -971 669  14   14                              263   -555 717  14   14   323   -1001                                                                               625  10   54                              264   213  789  14   14   324   -969 625  10   54                              265   309  789  14   14   325   -907 621  14   14                              266   341  957  14   14   326   -875 621  14   14                              267   277  957  14   14   327   -875 669  14   14                              268   -427 957  14   14   328   -907 669  14   14                              269   -491 957  14   14   329   -905 625  10   54                              270   329  527  134  10   330   -873 625  10   54                              271   455  529  10   366  331   -805 645  14   14                              272   457  887  766  10   332   -811 573  14   14                              273   1215 197  10   698  333   -811 693  14   14                              274   1217 195  86   10   334   -779 669  14   14                              275   1237 599  66   10   335   -779 621  14   14                              276   1235 601  10   342  336   -777 625  10   54                              277   433  935  810  10   337   -741 645  14   14                              278   431  601  10   342  338   -747 573  14   14                              279   281  599  158  10   339   -747 693  14   14                              280   279  601  10   54   340   -715 621  14   14                              281   313  671  102  10   341   -683 573  14   14                              282   407  673  10   318  342   -663 669  14   14                              283   409  983  894  10   343   -711 623  38   10                              284   995  1009 10   74   344   -681 625  10   54                              285   417  1007 586  10   345   -651 621  14   14                              286   343  961  10   30   346   -619 621  14   14                              287   265  1051 338  10   347   -619 669  14   14                              288   595  1053 10   30   348   -651 669  14   14                              289   281  983  38   10   349   -649 625  10   54                              290   279  961  10   30   350   -617 625  10   54                              291   217  791  102  10   351   -1195                                                                               933  14   14                              292   231  769  10   30   352   -1195                                                                               813  14   14                              293   -359 767  54   10   353   -1163                                                                               837  14   14                              294   -361 721  10   54   354   -1163                                                                               885  14   14                              295   -551 767  54   10   355   -1131                                                                               933  14   14                              296   -553 721  10   54   356   -1131                                                                               813  14   14                              297   -551 671  70   10   357   -1161                                                                               841  10   54                              298   -487 959  70   10   358   -1093                                                                               861  14   14                              299   -425 961  10   30   359   -1099                                                                               933  14   14                              300   -423 983  598  10   360   -1099                                                                               813  14   14                              361   -1067                                                                               837  14   14   421   -871 959  70   10                              362   -1067                                                                               885  14   14   422   -605 1009 10   74                              363   -1035                                                                               933  14   14   423   -647 1007 50   10                              364   -1035                                                                               813  14   14   424   -649 961  10   54                              365   -1065                                                                               841  10   54   425   -711 959  70   10                              366   -907 933  14   14   426   -1175                                                                               503  550  10                              367   -843 933  14   14   427   -1159                                                                               551  198  10                              368   -779 933  14   14   428   -617 601  10   30                              369   -779 813  14   14   429   - 807                                                                               599  198  10                              370   -843 813  14   14   430   -809 601  10   54                              371   -907 813  14   14   431   -871 647  70   10                              372   -875 885  14   14   432   -905 601  10   30                              373   -875 837  14   14   433   -1063                                                                               599  166  10                              374   -811 885  14   14   434   -1065                                                                               601  10   54                              375   -811 837  14   14   435   -1063                                                                               647  38   10                              376   -871 887  70   10   436   -1159                                                                               647  38   10                              377   -809 841  10   54   437   -775 647  38   10                              378   -871 839  70   10   438   -679 623  38   10                              379   -747 933  14   14   439   -759 743  134  10                              380   -683 933  14   14   440   -761 721  10   30                              381   -619 933  14   14   441   -1159                                                                               719  406  10                              382   -619 813  14   14   442   -1161                                                                               721  10   78                              383   -683 813  14   14   443   -1065                                                                               745  10   54                              384   -747 813  14   14   444   -1063                                                                               743  230  10                              385   -715 885  14   14   445   -1159                                                                               863  70   10                              386   -715 837  14   14   446   470  -763 40   86                              387   -651 885  14   14   447   1100 -780 40   120                             388   -651 837  14   14   448   519  -653 10   10                              389   -711 887  70   10   449   515  -605 10   10                              390   -649 841  10   54   450   515  -685 10   10                              391   -711 839  70   10   451   535  -669 10   10                              392   -635 501  14   14   452   535  -637 10   10                              393   -843 501  14   14   453   537  -665 6    34                              394   -1179                                                                               501  14   14   454   499  -651 22   6                               395   -1083                                                                               525  14   14   455   559  -653 10   10                              396   -699 525  14   14   456   555  -605 10   10                              397   -939 717  14   14   457   555  -685 10   10                              398   -635 741  14   14   458   575  -637 10   10                              399   -843 741  14   14   459   595  -669 10   10                              400   -891 741  14   14   460   595  -605 10   10                              401   -987 741  14   14   461   579  -635 22   6                               402   -1163                                                                               741  14   14   462   597  -665 6    34                              403   - 1179                                                                              981  14   14   463   619  -653 10   10                              404   -971 549  14   14   464   615  -605 10   10                              405   -1163                                                                               549  14   14   465   615  -685 10   10                              406   -1195                                                                               549  14   14   466   635  -669 10   10                              407   -1163                                                                               789  14   14   467   635  -637 10   10                              408   -1067                                                                               789  14   14   468   637  -665 6    34                              409   -875 957  14   14   469   599  -651 22   6                               410   -811 957  14   14   470   659  -653 10   10                              411   -715 957  14   14   471   655  -605 10   10                              412   -651 957  14   14   472   655  -685 10   10                              413   -1079                                                                               527  1414 10   473   675  -669 10   10                              414   -1283                                                                               195  66   10   474   675  -637 10   10                              415   -1225                                                                               197  10   362  475   677  -665 6    34                              416   -1223                                                                               551  38   10   476   639  -651 22   6                               417   -1283                                                                               983  114  10   477   699  -653 10   10                              418   -1005                                                                               1009 10   74   478   695  -605 10   10                              419   -1003                                                                               1007 138  10   479   695  -685 10   10                              420   -873 961  10   54   480   715  -669 10   10                              481   715  -637 10   10   541   1055 -685 10   10                              482   717  -665 6    34   542   1075 -669 10   10                              483   679  -651 22   6    543   1075 -637 10   10                              484   739  -653 10   10   544   1077 -665 6    34                              485   735  -605 10   10   545   1051 -797 10   10                              486   735  -685 10   10   546   1055 -845 10   10                              487   755  -669 10   10   547   1055 -765 10   10                              488   755  -637 10   10   548   1035 -781 10   10                              489   757  -665 6    34   549   1035 -813 10   10                              490   719  -651 22   6    550   1015 -845 10   10                              491   779  -653 10   10   551   1015 -765 10   10                              492   775  -605 10   10   552   995  -781 10   10                              493   775  -685 10   10   553   995  -813 10   10                              494   795  -669 10   10   554   975  -845 10   10                              495   795  -637 10   10   555   975  -765 10   10                              496   797  -665 6    34   556   999  -811 42   6                               497   759  -651 22   6    557   997  -809 6    34                              498   819  -653 10   10   558   999  -779 42   6                               499   815  -605 10   10   559   935  -845 10   10                              500   815  -685 10   10   560   935  -765 10   10                              501   835  -669 10   10   561   915  -781 10   10                              502   835  -637 10   10   562   915  -813 10   10                              503   837  -665 6    34   563   917  -809 6    34                              504   799  -651 22   6    564   891  -797 10   10                              505   859  -653 10   10   565   895  -845 10   10                              506   855  -605 10   10   566   895  -765 10   10                              507   855  -685 10   10   567   875  -781 10   10                              508   875  -669 10   10   568   875  -813 10   10                              509   875  -637 10   10   569   877  -809 6    34                              510   877  -665 6    34   570   899  -795 22   6                               511   839  -651 22   6    571   851  -797 10   10                              512   899  -653 10   10   572   855  -845 10   10                              513   895  - 605                                                                               10   10   573   855  -765 10   10                              514   895  -685 10   10   574   835  -781 10   10                              515   915  -669 10   10   575   835  -813 10   10                              516   915  -637 10   10   576   837  -809 6    34                              517   917  -665 6    34   577   859  -795 22   6                               518   879  -651 22   6    578   811  -797 10   10                              519   939  -653 10   10   579   815  -845 10   10                              520   935  -605 10   10   580   815  -765 10   10                              521   935  -685 10   10   581   795  -781 10   10                              522   955  -669 10   10   582   795  -813 10   10                              523   955  -637 10   10   583   797  -809 6    34                              524   957  -665 6    34   584   819  -795 22   6                               525   919  -651 22   6    585   771  -797 10   10                              526   979  -653 10   10   586   775  -845 10   10                              527   975  -605 10   10   587   775  -765 10   10                              528   975  -685 10   10   588   755  -781 10   10                              529   995  -669 10   10   589   755  -813 10   10                              530   995  -637 10   10   590   757  -809 6    34                              531   997  -665 6    34   591   779  -795 22   6                               532   959  -651 22   6    592   731  -797 10   10                              533   1019 -653 10   10   593   735  -845 10   10                              534   1015 -605 10   10   594   735  -765 10   10                              535   1015 -685 10   10   595   715  -781 10   10                              536   1035 -669 10   10   596   715  -813 10   10                              537   1035 -637 10   10   597   717  -809 6    34                              538   1037 -665 6    34   598   739  -795 22   6                               539   999  -651 22   6    599   691  -797 10   10                              540   1055 -605 10   10   600   695  -845 10   10                              601   695  -765 10   10   661   -1005                                                                               -1103                                                                               10   276                             602   675  -781 10   10   662   519  -603 602  6                               603   675  -813 10   10   663   579  -843 542  6                               604   677  -809 6    34   664   479  -763 582  6                               605   699  -795 22   6    665   1017 -761 6    82                              606   651  -797 10   10   666   479  -683 582  6                               607   655  -845 10   10   667   999  -859 182  6                               608   655  -765 10   10   668   577  -889 6    18                              609   635  -781 10   10   669   579  -891 422  6                               610   635  -813 10   10   670   517  -921 6    66                              611   637  -809 6    34   671   519  -923 82   6                               612   659  -795 22   6    672   449  -651 72   6                               613   611  -797 10   10   673   419  -635 122  6                               614   615  -845 10   10   674   557  -649 6    34                              615   615  -765 10   10   675   389  -619 172  6                               616   595  -781 10   10   676   1039 -667 42   6                               617   595  -813 10   10   677   1077 -793 6    130                             618   597  -809 6    34   678   1059 -795 22   6                               619   619  -795 22   6    679   957  -729 6    34                              620   575  -845 10   10   680   939  -731 22   6                               621   575  -765 10   10   681   597  -745 6    34                              622   555  -781 10   10   682   539  -747 62   6                               623   555  -813 10   10   683   539  -875 22   6                               624   557  -809 6    34   684   557  -873 6    18                              625   515  -861 10   10   685   0    0    0    0                               626   515  -813 10   10                                                        627   515  -781 10   10                                                        628   535  -749 10   10                                                        629   535  -781 10   10                                                        630   535  -813 10   10                                                        631   537  -809 6    34                                                        632   517  -809 6    34                                                        633   595  -717 10   10                                                        634   935  -733 10   10                                                        635   535  -877 10   10                                                        636   575  -877 10   10                                                        637   955  -701 10   10                                                        638   535  -749 10   10                                                        639   595  -749 10   10                                                        640   515  -861 10   10                                                        641   555  -861 10   10                                                        642   995  -861 10   10                                                        643   1035 -861 10   10                                                        644   1117 -605 186  10                                                        645   1115 -841 10   244                                                       646   1175 -1003                                                                               10   148                                                       647   1177 -1005                                                                               126  10                                                        648   995  -1103                                                                               10   216                                                       649   595  -1103                                                                               10   184                                                       650   475  -923 10   166                                                       651   197  -925 286  10                                                        652   195  -1103                                                                               10   186                                                       653   445  -893 10   246                                                       654   -203 -895 656  10                                                        655   -205 -1103                                                                               10   216                                                       656   415  -863 10   232                                                       657   -603 -865 1026 10                                                        658   -605 -1103                                                                               10   246                                                       659   385  -833 10   218                                                       660   -1003                                                                               -835 1396 10                                                        __________________________________________________________________________

                                      TABLE II                                     __________________________________________________________________________           WORD WORD WORD WORD       WORD WORD WORD WORD                            RECORD                                                                               1    2    3    4    RECORD                                                                               1    2    3    4                               NO.   X    Y    XL   YL   NO.   X    Y    XL   YL                              __________________________________________________________________________     1     1    5    685  1    61    809  759  10   10                              2     3    733  0    70   62    805  807  10   10                              3     1606 1350 0    10   63    805  727  10   10                              4     -1204                                                                               -900 0    0    64    825  743  10   10                              5     803  900  0    8    65    825  775  10   10                              6     196  692  240  240  66    827  747  6    34                              7     436  772  20   80   67    789  761  22   6                               8     196  292  240  240  68    849  759  10   10                              9     436  372  20   80   69    845  807  10   10                              10    596  92   240  240  70    845  727  10   10                              11    676  332  80   20   71    865  743  10   10                              12    713  577  200  10   72    865  775  10   10                              13    711  309  10   276  73    867  747  6    34                              14    803  0    0    0    74    829  761  22   6                               15    803  900  0    9    75    889  759  10   10                              16    193  92   240  240  76    885  807  10   10                              17    273  332  80   20   77    885  727  10   10                              18    593  92   240  240  78    905  743  10   10                              19    673  332  80   20   79    905  775  10   10                              20    710  517  203  10   80    907  747  6    34                              21    708  309  10   216  81    869  761  22   6                               22    310  547  603  10   82    905  631  10   10                              23    308  309  10   246  83    905  599  10   10                              24    110  577  803  10   84    907  603  6    34                              25    803  0    0    0    85    881  615  10   10                              26    803  900  0    139  86    885  567  10   10                              27    190  92   240  240  87    885  647  10   10                              28    270  332  80   20   88    865  631  10   10                              29    590  92   240  240  89    865  599  10   10                              30    670  332  80   20   90    867  603  6    34                              31    580  649  40   86   91    889  617  22   6                               32    629  759  10   10   92    841  615  10   10                              33    625  807  10   10   93    845  567  10   10                              34    625  727  10   10   94    845  647  10   10                              35    645  743  10   10   95    825  631  10   10                              36    645  775  10   10   96    825  599  10   10                              37    647  747  6    34   97    827  603  6    34                              38    609  761  22   6    98    849  617  22   6                               39    669  759  10   10   99    801  615  10   10                              40    665  807  10   10   100   805  567  10   10                              41    665  727  10   10   101   805  647  10   10                              42    685  775  10   10   102   785  631  10   10                              43    705  743  10   10   103   785  599  10   10                              44    705  807  10   10   104   787  603  6    34                              45    689  777  22   6    105   809  617  22   6                               46    707  747  6    34   106   761  615  10   10                              47    729  759  10   10   107   765  567  10   10                              48    725  807  10   10   108   765  647  10   10                              49    725  727  10   10   109   745  631  10   10                              50    745  743  10   10   110   745  599  10   10                              51    745  775  10   10   111   747  603  6    34                              52    747  747  6    34   112   769  617  22   6                               53    709  761  22   6    113   721  615  10   10                              54    769  759  10   10   114   725  567  10   10                              55    765  807  10   10   115   725  647  10   10                              56    765  727  10   10   116   705  631  10   10                              57    785  743  10   10   117   705  599  10   10                              58    785  775  10   10   118   707  603  6    34                              59    787  747  6    34   119   729  617  22   6                               60    749  761  22   6    120   685  567  10   10                              121   685  647  10   10   181   106  761  22   6                               122   665  631  10   10   182   166  759  10   10                              123   665  599  10   10   183   162  807  10   10                              124   667  603  6    34   184   162  727  10   10                              125   625  551  10   10   185   182  743  10   10                              126   625  599  10   10   186   182  775  10   10                              127   625  631  10   10   187   184  747  6    34                              128   645  663  10   10   188   146  761  22   6                               129   645  631  10   10   189   206  759  10   10                              130   645  599  10   10   190   202  807  10   10                              131   647  603  6    34   191   202  727  10   10                              132   627  603  6    34   192   222  743  10   10                              133   705  695  10   10   193   222  775  10   10                              134   645  535  10   10   194   224  747  6    34                              135   685  535  10   10   195   186  761  22   6                               136   645  663  10   10   196   246  759  10   10                              137   705  663  10   10   197   242  807  10   10                              138   625  551  10   10   198   242  727  10   10                              139   665  551  10   10   199   262  743  10   10                              140   705  309  10   184  200   262  775  10   10                              141   585  489  10   166  201   264  747  6    34                              142   307  487  286  10   202   226  761  22   6                               143   305  309  10   186  203   286  759  10   10                              144   555  519  10   246  204   282  807  10   10                              145   110  517  453  10   205   282  727  10   10                              146   525  549  10   232  206   302  743  10   10                              147   110  547  423  10   207   302  775  10   10                              148   495  579  10   218  208   304  747  6    34                              149   110  577  393  10   209   266  761  22   6                               150   629  809  284  6    210   326  759  10   10                              151   689  569  224  6    211   322  807  10   10                              152   589  649  324  6    212   322  727  10   10                              153   589  729  324  6    213   342  743  10   10                              154   687  523  6    18   214   342  775  10   10                              155   689  521  224  6    215   344  747  6    34                              156   627  491  6    66   216   306  761  22   6                               157   629  489  82   6    217   362  807  10   10                              158   559  761  72   6    218   362  727  10   10                              159   529  777  122  6    219   382  743  10   10                              160   667  763  6    34   220   382  775  10   10                              161   499  793  172  6    221   384  747  6    34                              162   707  667  6    34   222   358  615  10   10                              163   649  665  62   6    223   362  567  10   10                              164   649  537  22   6    224   362  647  10   10                              165   667  539  6    18   225   342  631  10   10                              166   803  0    0    0    226   342  599  10   10                              167   803  900  0    112  227   322  567  10   10                              168   587  292  240  240  228   322  647  10   10                              169   567  372  20   80   229   302  631  10   10                              170   587  692  240  240  230   302  599  10   10                              171   567  772  20   80   231   282  567  10   10                              172   187  92   240  240  232   282  647  10   10                              173   267  332  80   20   233   306  601  42   6                               174   407  632  40   120  234   304  603  6    34                              175   126  759  10   10   235   306  633  42   6                               176   122  807  10   10   236   242  567  10   10                              177   122  727  10   10   237   242  647  10   10                              178   142  743  10   10   238   222  631  10   10                              179   142  775  10   10   239   222  599  10   10                              180   144  747  6    34   240   224  603  6    34                              241   198  615  10   10   301   436  572  20   80                              242   202  567  10   10   302   196  92   240  240                             243   202  647  10   10   303   436  172  20   80                              244   182  631  10   10   304   456  187  40   370                             245   182  599  10   10   305   493  187  420  10                              246   184  603  6    34   306   493  547  420  10                              247   206  617  22   6    307   493  523  420  10                              248   158  615  10   10   308   811  525  10   30                              249   162  567  10   10   309   525  427  388  10                              250   162  647  10   10   310   523  309  10   126                             251   142  631  10   10   311   525  307  388  10                              252   142  599  10   10   312   521  233  14   14                              253   144  603  6    34   313   553  233  14   14                              254   166  617  22   6    314   553  281  14   14                              255   118  615  10   10   315   521  281  14   14                              256   122  567  10   10   316   523  237  10   54                              257   122  647  10   10   317   555  237  10   54                              258   126  617  22   6    318   591  257  14   14                              259   242  679  10   10   319   585  185  14   14                              260   262  711  10   10   320   585  305  14   14                              261   302  551  10   10   321   617  233  14   14                              262   342  551  10   10   322   649  185  14   14                              263   424  807  186  10   323   649  281  14   14                              264   422  571  10   244  324   621  235  38   10                              265   482  409  10   148  325   651  237  10   54                              266   484  407  126  10   326   687  257  14   14                              267   302  309  10   216  327   681  185  14   14                              268   110  809  318  6    328   681  305  14   14                              269   110  569  318  6    329   713  281  14   14                              270   110  649  258  6    330   713  233  14   14                              271   324  651  6    82   331   745  233  14   14                              272   110  729  258  6    332   745  281  14   14                              273   306  553  182  6    333   715  237  10   54                              274   110  521  198  6    334   747  237  10   54                              275   346  745  42   6    335   809  233  14   14                              276   384  619  6    130  336   841  233  14   14                              277   366  617  22   6    337   841  281  14   14                              278   264  683  6    34   338   809  281  14   14                              279   246  681  22   6    339   811  237  10   54                              280   0    900  0    0    340   843  237  10   54                              281   803  900  0    6    341   905  185  14   14                              282   587  192  240  240  342   905  305  14   14                              283   567  272  20   80   343   521  545  14   14                              284   587  592  240  240  344   521  425  14   14                              285   567  672  20   80   345   553  449  14   14                              286   522  709  10   253  346   553  497  14   14                              287   524  707  86   10   347   585  545  14   14                              288   -2409                                                                               0    0    0    348   585  425  14   14                              289   803  900  0    6    349   555  453  10   54                              290   196  592  240  240  350   623  473  14   14                              291   436  672  20   80   351   617  545  14   14                              292   196  192  240  240  352   617  425  14   14                              293   436  272  20   80   353   649  449  14   14                              294   433  707  66   10   354   649  497  14   14                              295   491  709  10   253  355   681  545  14   14                              296   0    900  0    0    356   681  425  14   14                              297   803  900  0    109  357   651  453  10   54                              298   596  692  240  240  358   809  545  14   14                              299   676  672  80   20   359   873  545  14   14                              300   196  492  240  240  360   873  425  14   14                              361   809  425  14   14   421   392  525  10   30                              362   841  497  14   14   422   110  427  803  10                              363   841  449  14   14   423   110  307  803  10                              364   905  497  14   14   424   328  309  10   126                             365   905  449  14   14   425   520  309  10   126                             366   845  499  70   10   426   896  257  14   14                              367   907  453  10   54   427   902  185  14   14                              368   845  451  70   10   428   902  305  14   14                              369   873  113  14   14   429   870  281  14   14                              370   537  113  14   14   430   870  233  14   14                              371   633  137  14   14   431   872  237  10   54                              372   777  329  14   14   432   832  257  14   14                              373   873  353  14   14   433   838  185  14   14                              374   825  353  14   14   434   838  305  14   14                              375   729  353  14   14   435   806  281  14   14                              376   553  353  14   14   436   806  233  14   14                              377   537  593  14   14   437   808  237  10   54                              378   745  161  14   14   438   842  259  38   10                              379   553  161  14   14   439   768  257  14   14                              380   521  161  14   14   440   774  185  14   14                              381   553  401  14   14   441   774  305  14   14                              382   649  401  14   14   442   742  281  14   14                              383   841  569  14   14   443   742  233  14   14                              384   905  569  14   14   444   744  237  10   54                              385   637  139  276  10   445   778  259  38   10                              386   491  62   10   109  446   704  257  14   14                              387   493  163  38   10   447   710  185  14   14                              388   433  595  114  10   448   710  305  14   14                              389   711  621  10   74   449   678  281  14   14                              390   713  619  138  10   450   678  233  14   14                              391   843  573  10   54   451   680  237  10   54                              392   845  571  70   10   452   714  259  38   10                              393   541  115  372  10   453   640  257  14   14                              394   557  163  198  10   454   646  185  14   14                              395   907  213  10   54   455   646  305  14   14                              396   845  259  70   10   456   614  281  14   14                              397   811  213  10   30   457   614  233  14   14                              398   653  211  166  10   458   616  237  10   54                              399   651  213  10   54   459   650  259  38   10                              400   653  259  38   10   460   576  257  14   14                              401   557  259  38   10   461   582  185  14   14                              402   557  331  406  10   462   582  305  14   14                              403   555  333  10   78   463   550  281  14   14                              404   651  357  10   54   464   550  233  14   14                              405   653  355  230  10   465   552  237  10   54                              406   557  475  70   10   466   586  259  38   10                              407   803  0    0    0    467   512  257  14   14                              408   803  900  0    190  468   518  185  14   14                              409   593  692  240  240  469   518  305  14   14                              410   673  672  80   20   470   486  281  14   14                              411   193  692  240  240  471   486  233  14   14                              412   273  672  80   20   472   488  237  10   54                              413   705  622  208  20   473   522  259  38   10                              414   703  624  20   76   474   448  257  14   14                              415   110  187  803  10   475   454  185  14   14                              416   110  547  803  10   476   454  305  14   14                              417   520  525  10   30   477   422  281  14   14                              418   110  523  418  10   478   422  233  14   14                              419   168  525  10   30   479   424  237  10   54                              420   296  525  10   30   480   458  259  38   10                              481   390  185  14   14   541   554  379  54   10                              482   390  305  14   14   542   552  333  10   54                              483   358  281  14   14   543   362  379  54   10                              484   358  233  14   14   544   360  333  10   54                              485   360  237  10   54   545   362  283  70   10                              486   390  545  14   14   546   426  571  70   10                              487   454  545  14   14   547   488  573  10   30                              488   518  545  14   14   548   490  595  423  10                              489   518  425  14   14   549   108  257  14   14                              490   454  425  14   14   550   134  281  14   14                              491   390  425  14   14   551   134  233  14   14                              492   422  497  14   14   552   136  237  10   54                              493   422  449  14   14   553   172  257  14   14                              494   486  497  14   14   554   166  185  14   14                              495   486  449  14   14   555   166  305  14   14                              496   426  499  70   10   556   198  233  14   14                              497   488  453  10   54   557   230  185  14   14                              498   426  451  70   10   558   230  281  14   14                              499   582  545  14   14   559   202  235  38   10                              500   582  425  14   14   560   232  237  10   54                              501   614  449  14   14   561   262  233  14   14                              502   614  497  14   14   562   294  233  14   14                              503   616  453  10   54   563   294  281  14   14                              504   652  473  14   14   564   262  281  14   14                              505   646  545  14   14   565   264  237  10   54                              506   646  425  14   14   566   296  237  10   54                              507   678  449  14   14   567   134  545  14   14                              508   678  497  14   14   568   134  425  14   14                              509   680  453  10   54   569   166  545  14   14                              510   618  475  38   10   570   230  545  14   14                              511   716  473  14   14   571   294  545  14   14                              512   710  545  14   14   572   294  425  14   14                              513   710  425  14   14   573   230  425  14   14                              514   742  449  14   14   574   166  425  14   14                              515   742  497  14   14   575   198  497  14   14                              516   744  453  10   54   576   198  449  14   14                              517   682  475  38   10   577   262  497  14   14                              518   780  473  14   14   578   262  449  14   14                              519   774  545  14   14   579   202  499  70   10                              520   774  425  14   14   580   264  453  10   54                              521   806  449  14   14   581   202  451  70   10                              522   806  497  14   14   582   278  113  14   14                              523   808  453  10   54   583   214  137  14   14                              524   746  475  38   10   584   278  353  14   14                              525   844  473  14   14   585   198  569  14   14                              526   838  545  14   14   586   262  569  14   14                              527   838  425  14   14   587   110  139  803  10                              528   870  449  14   14   588   308  621  10   74                              529   870  497  14   14   589   266  619  50   10                              530   872  453  10   54   590   264  573  10   54                              531   810  475  38   10   591   202  571  70   10                              532   902  545  14   14   592   110  115  178  10                              533   902  425  14   14   593   296  213  10   30                              534   874  475  38   10   594   106  211  198  10                              535   598  377  14   14   595   138  259  38   10                              536   406  377  14   14   596   234  235  38   10                              537   550  329  14   14   597   154  355  134  10                              538   358  329  14   14   598   152  333  10   30                              539   486  569  14   14   599   803  0    0    0                               540   422  569  14   14   600   803  900  0    117                             601   590  692  240  240  661   259  449  14   14                              602   670  672  80   20   662   259  497  14   14                              603   190  692  240  240  663   261  453  10   54                              604   270  672  80   20   664   199  475  38   10                              605   476  308  28   128  665   297  473  14   14                              606   486  424  20   216  666   291  545  14   14                              607   110  622  394  20   667   291  425  14   14                              608   110  187  351  10   668   323  449  14   14                              609   110  547  255  10   669   323  497  14   14                              610   110  427  383  10   670   325  453  10   54                              611   110  307  383  10   671   263  475  38   10                              612   451  185  14   14   672   355  545  14   14                              613   451  305  14   14   673   355  425  14   14                              614   419  281  14   14   674   387  449  14   14                              615   419  233  14   14   675   387  497  14   14                              616   421  237  10   54   676   389  453  10   54                              617   381  257  14   14   677   419  497  14   14                              618   387  185  14   14   678   451  497  14   14                              619   387  305  14   14   679   451  449  14   14                              620   355  233  14   14   680   419  449  14   14                              621   323  185  14   14   681   421  453  10   54                              622   323  281  14   14   682   453  453  10   54                              623   327  235  38   10   683   435  137  14   14                              624   325  237  10   54   684   523  617  14   14                              625   285  257  14   14   685   459  593  14   14                              626   291  185  14   14   686   419  593  14   14                              627   291  305  14   14   687   371  657  14   14                              628   259  281  14   14   688   339  377  14   14                              629   259  233  14   14   689   279  593  14   14                              630   261  237  10   54   690   271  593  14   14                              631   295  259  38   10   691   279  657  14   14                              632   221  257  14   14   692   271  657  14   14                              633   227  185  14   14   693   323  401  14   14                              634   227  305  14   14   694   419  401  14   14                              635   195  281  14   14   695   451  569  14   14                              636   195  233  14   14   696   387  569  14   14                              637   197  237  10   54   697   439  139  134  10                              638   231  259  38   10   698   565  141  10   366                             639   157  257  14   14   699   567  499  346  10                              640   163  185  14   14   700   543  547  370  10                              641   163  305  14   14   701   541  213  10   342                             642   131  281  14   14   702   391  211  158  10                              643   131  233  14   14   703   389  213  10   54                              644   133  237  10   54   704   423  283  102  10                              645   167  259  38   10   705   517  285  10   318                             646   103  259  38   10   706   519  595  394  10                              647   105  473  14   14   707   527  619  386  10                              648   131  449  14   14   708   453  573  10   30                              649   131  497  14   14   709   375  663  338  10                              650   133  453  10   54   710   705  665  10   30                              651   169  473  14   14   711   391  595  38   10                              652   163  545  14   14   712   389  573  10   30                              653   163  425  14   14   713   327  403  102  10                              654   195  449  14   14   714   341  381  10   30                              655   195  497  14   14   715   110  595  175  10                              656   197  453  10   54   716   279  667  34   10                              657   135  475  38   10   717   110  139  335  10                              658   233  473  14   14   718   803  0    0    0                               659   227  545  14   14   719   803  900  0    14                              660   227  425  14   14   720   587  92   240  240                             721   567  172  20   80                                                        722   587  492  240  240                                                       723   567  572  20   80                                                        724   187  692  240  240                                                       725   267  672  80   20                                                        726   110  499  420  10                                                        727   522  62   10   445                                                       728   544  211  66   10                                                        729   542  213  10   342                                                       730   110  547  440  10                                                        731   110  595  500  10                                                        732   302  621  10   74                                                        733   110  619  200  10                                                        734   -1205                                                                               -900 0    0                                                         735   0    0    0    0                                                         736   23   8224 8224 8224                                                      __________________________________________________________________________ 

What is claimed is:
 1. The method of scanning a pattern on a work piece where the pattern covers a pattern area and where the pattern area is divided into a plurality of contiguous partitions each having a partition area smaller than said pattern area, the steps comprising,generating for an exposing beam a scan field having a scan area greater than said partition area, relatively moving said scan field and said work piece to successively move said scan field to scan each of said partitions whereby an overlapping boundary region exists between the scan field relative to one of said partitions and the scan field relative to another one of said partitions contiguous to said one of said partitions, selectively controlling the exposing beam in said overlapping boundary region to selectively expose portions of said pattern in said boundary region either in connection with the scan field of said one of said partitions or in connection with the scan field of said another one of said partitions.
 2. The method of claim 1 including controlling said exposing beam in said overlapping boundary region to expose portions of said pattern, located in said boundary region and located within said one of said partitions, only in connection with the scan field of said another one of said partitions.
 3. The method of claim 1 wherein said pattern is defined by a plurality of abutting shapes having a location and size identified with respect to a common origin for said pattern area, the additional step comprising allocating said shapes among said partitions in accordance with a predetermined algorithm whereby a single exposure of all portions of each shape occurs.
 4. The method of claim 3 wherein said algorithm includes the step of allocating shapes contained entirely within said one of said partitions entirely to said one of said partitions.
 5. The method of claim 3 wherein said algorithm includes the step of allocating a shape, contained in said one of said partitions and contained only within that portion of said another one of said partitions within said overlapping boundary region, entirely to said one of said partitions.
 6. The method of claim 4 wherein said algorithm includes the step of exposing a shape which is contained entirely within said overlapping boundary region entirely within said one or said another one of said partitions having the largest percentage of the area of said shape.
 7. The method of claim 3 wherein said algorithm is executed for each shape first in one direction to determine partitioning along one axis and thereafter in an orthogonal direction to determine partitioning along a second axis orthogonal to said first axis.
 8. The method of claim 3 wherein said partitions are arrayed in orthogonal rows and columns and wherein said algorithm is executed first with respect to said columns to determine allocation of shapes within each column of said partitions and whereafter said algorithm is executed with respect to rows for each of the shapes in each of said columns whereby the row and column allocation of each shape is determined.
 9. The method of claim 8 including the step of sorting the shapes allocated to each partition, exposing each shape allocated to a particular partition, and relatively moving the scan field and the work piece to a next partition, and exposing each shape allocated to said next partition.
 10. The method of claim 9 wherein said shapes are rectangles.
 11. An apparatus for scanning a pattern on a work piece where the pattern covers a pattern area and where the pattern area is divided into a plurality of contiguous partitions each having a partition area smaller than said pattern area, comprising,means for generating a scan field having a scan area greater than said partition area, means for relatively moving said scan field and said work piece to successively move said scan field to scan each of said partitions whereby an overlapping boundary region exists between the scan field relative to one of said partitions and the scan field relative to another one of said partitions contiguous to said one of said partitions, control means for selectively controlling the exposing beam in said overlapping boundary region to selectively expose portions of said pattern in said boundary region either in connection with the scan field of said one of said partitions or in connection with the scan field of said another one of said partitions.
 12. The apparatus of claim 11 wherein said control means includes means for controlling said exposing beam in said overlapping boundary region to expose a portion of said pattern, located in said boundary region and located within said one of said partitions, only in connection with the scan field of said another one of said partitions.
 13. The method of scanning a pattern on a resist-coated work piece to form semiconductor circuits where the pattern covers a pattern area and where the pattern area is divided into a plurality of partitions each having a partition area smaller than said pattern area where adjacent partitions abut along a partition boundary, the steps comprising,generating for an exposing beam, a scan field having a scan area greater than said partition area, relatively positioning said scan field and said work piece with some positional error to successively move said scan field to scan each of said partitions whereby an overlapping boundary region exists between the scan field relative to one of said partitions and the scan field relative to another one of said partitions contiguous to said one of said partitions, said overlapping boundary region containing portions of said pattern defining particular dimensions of the semiconductor circuit, said positional error being substantial with respect to said particular dimensions, selectively controlling the exposing beam in said overlapping boundary region to selectively expose portions of said pattern in said boundary region either in connection with the scan field of said one of said partitions or in connection with the scan field of said another one of said partitions whereby said particular dimensions are exposed entirely in said one or in said another one of said partitions so that said positional error does not alter said particular dimensions.
 14. An apparatus for scanning a pattern on a resist-coated work piece to form semiconductor circuits where the pattern covers a pattern area and where the pattern area is divided into a plurality of partitions each having a partition area smaller than said pattern area where adjacent partitions abut along a partition boundary, comprising,means for generating for an exposing beam, a scan field having a scan area greater than said partition area, means for relatively positioning said scan field and said work piece with some positional error to successively move said scan field to scan each of said partitions whereby an overlapping boundary region exists between the scan field relative to one of said partitions and the scan field relative to another one of said partitions contiguous to said one of said partitions, said overlapping boundary region containing portions of said pattern defining particular dimensions of the semiconductor circuit, said positional error being substantial with respect to said particular dimensions, means for selectively controlling the exposing beam in said overlapping boundary region to selectively expose portions of said pattern in said boundary region either in connection with the scan field of said one of said partitions or in connection with the scan field of said another one of said partitions whereby said particular dimensions are exposed entirely in said one or in said another one of said partitions so that said positional error does not alter said particular dimensions.
 15. An electron beam apparatus for scanning a pattern on a resist-coated work piece to form semiconductor circuits where the pattern covers a pattern area and where the pattern area is divided into a plurality of partitions each having a partition area smaller than said pattern area where adjacent partitions abut along a partition boundary, comprising,an electron beam column apparatus having means for generating an electron beam, blanking means for selectively blanking the electron beam in connection with scanning a pattern, and deflection means for deflecting the electron beam, generator means for providing control signals to said deflection means to scan said electron beam over a scan field having a scan area greater than said partition area, positioning means for positioning said work piece at commanded positions relative to said scan field, control means for successively supplying commanded positions to said positioning means whereby said work piece is positioned relative to said scan field to scan each of said partitions with an overlapping boundary region between the scan field relative to one of said partitions and the scan field relative to another adjacent one of said partitions, said overlapping boundary region containing portions of said pattern defining particular dimensions of a semiconductor circuit, said one of and said adjacent one of said partitions abutting in said boundary region with some positional error, means for measuring the actual position of said electron beam on said work piece, means for forming error signals as a function of the difference between said commanded position and said actual position, means for adding said error signals to said control signals whereby said electron beam is positioned more accurately relative to said work piece, means for selectively controlling said blanking means for selectively blanking the electron beam during the scanning of said overlapping boundary region to selectively expose portions of said pattern in said boundary region either in connection with the scan field of said one of said partitions or in connection with the scan field of said another one of said partitions whereby said particular dimensions are exposed entirely in said one or in said another one of said partitions so that said positional error does not affect said particular dimensions.
 16. The apparatus of claim 15 wherein said means for selectively controlling includes memory means for separately storing digital representations of portions of the pattern for each separate partition area and includes means for accessing said digital representations for each separate partition area one at a time for each partition area.
 17. The apparatus of claim 16 wherein said generator means includes means for controlling said scanning for positions of said electron beam having corresponding digital representations in said memory means.
 18. The apparatus of claim 17 wherein said digital representations include X axis and Y axis representations. 